Nonadenomatous Tumors of the Pituitary and Sella Turcica

Transcription

REVIEW ARTICLE
Nonadenomatous Tumors of the Pituitary
and Sella Turcica
Benjamin Y. Huang, MD, MPH, and Mauricio Castillo, MD, FACR
Abstract: While pituitary adenomas make up over 90% of all sellar
masses, there are a number of less known tumors, both malignant
and benign, which may arise within the sella turcica. These include
relatively common tumors such as meningiomas and craniopharyngiomas, as well as extremely rare tumors such as pituitary
astrocytomas and granular cell tumors. Unfortunately, many of these
tumors lack characteristic imaging features, often making it
extremely difficult to distinguish them by imaging alone from the
more common pituitary adenoma. In this article, we review several
nonadenomatous tumors of the sella, with a focus on their clinical
features and typical MR imaging characteristics.
Key Words: nonadenomatous tumors, pituitary
(Top Magn Reson Imaging 2005;16:289Y299)
A
lthough pituitary adenomas are the most common sellar
tumors, accounting for more than 90% of sellar masses1
and 10% to 15% of all intracranial neoplasms,2 there are other
tumors that arise in the sella turcica. These tumors arise from
normal pituitary elements (craniopharyngiomas, pituitary
carcinomas, astrocytomas, and granular cell tumors) may be
of nonpituitary origin (meningiomas, germ cell tumors, and
lymphoma) or may be metastases.
Many of these nonadenomatous tumors lack specific
imaging characteristics and are often indistinguishable from
adenomas by imaging alone. In many instances, a definitive
diagnosis is made only postoperatively, and the final
histological diagnosis is often unexpected. Despite this,
there are imaging findings that may be helpful in suggesting
that a sellar lesion may not be an adenoma. In this article, we
review several nonadenomatous sellar tumors and their
imaging characteristics (Table 1).
CRANIOPHARYNGIOMAS
Craniopharyngiomas are common, benign neoplasms,
accounting for 2% to 5% of all intracranial tumors.2,3 They
have a bimodal age distribution with a primary peak between
5 and 14 years and a second smaller peak somewhere between
the fifth and seventh decades. Approximately two thirds occur
in individuals younger than 20 years.4,5 Craniopharyngiomas
From the Department of Radiology, University of North Carolina at Chapel
Hill, NC.
Reprints: M. Castillo, MD, FACR, CB no. 7510, Department of Radiology,
University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7510
(e-mail: [email protected]).
Copyright * 2005 by Lippincott Williams & Wilkins
Top Magn Reson Imaging
account for 5.6% to 13% of intracranial tumors in children
and are 10 to 20 times more common than adenomas in this
population.3,6 The incidence does not vary by race or sex.4
Craniopharyngiomas are derived from squamous cell
rests in the remnant of Rathke pouch between the adenohypophysis and neurohypophysis and can occur anywhere along
the path of the craniopharyngeal duct, from the nasopharynx
to the third ventricle.3,6,7 Most craniopharyngiomas have a
suprasellar component, with only 4% to 25% being purely
intrasellar.3,5,8 Two subtypes of craniopharyngioma have
been described: the adamantinomatous type, which is
predominantly a tumor of children and adolescents but
which can be seen at any age, and the papillary type, which is
seen almost exclusively in adults.9
Patients commonly present with nonendocrine symptoms, including headache, nausea, vomiting, and symptoms
related to compression of the optic chiasm.6 Endocrine
dysfunction is less common and may be manifested in
children as growth disturbances.2,3,6 Up to 80% of children
with craniopharyngiomas have endocrine dysfunction at
diagnosis, with 75% demonstrating growth hormone deficiency.10 Patients may present with hypopituitarism, hyperprolactinemia, or diabetes insipidus (DI).3 Treatment usually
consists of surgical resection with or without adjuvant
radiotherapy, based on whether gross total resection is
achieved. Recurrence is rare after gross total resection.
With subtotal resection, only 47% of patients are recurrencefree at 5 years, and only 38% are recurrence-free at 10 years.3
On magnetic resonance imaging (MRI), craniopharyngiomas can appear cystic, solid, or both.2,3 Cysts are seen
in 85% of craniopharyngiomas.11 Predominantly solid tumors
are 2 times more likely to be seen in adults than in children,
whereas predominantly cystic tumors are seen in children
roughly 50% of the time and less frequently in adults.3 Cysts
contain variable amounts of cholesterol, keratin, protein,
methemoglobin, and necrotic debris, which accounts for their
variable appearance on MRI.12 Cystic components are
typically hyperintense, and less commonly isointense, to
cerebrospinal fluid (CSF) on T1-weighted images.2 Fluiddebris levels can be seen within the cysts. Solid components
have variable signal intensities, and they usually enhance
after gadolinium administration.2,13
Calcification is typical of craniopharyngiomas and is
present in approximately two thirds of all cases; tumor
calcification is seen in approximately 90% of childhood
craniopharyngiomas and in 50% to 70% of adult craniopharyngiomas.2,7,14 Calcification is rare in papillary-type craniopharyngiomas.9 Computed tomography is the preferred
modality for detecting calcification.13
& Volume 16, Number 4, July 2005
Copyr ight © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
289
Huang and Castillo
TABLE 1. Nonadenomatous Tumors of the Sella Turcica
Tumors of pituitary
origin
Nonpituitary origin
Craniopharyngioma/Rathke cleft cyst
Pituitary carcinoma
Astrocytoma (pilocytic or pituicytoma)
Granular cell tumor
Gangliocytoma and MGA
Meningioma
Germ cell tumors
Primary CNS lymphoma
Dermoid/epidermoid
Schwannoma
Metastases (breast and lung cancers most common)
Solid craniopharyngiomas can be difficult to distinguish
from adenomas. However, the apparent diffusion coefficient
of craniopharyngiomas is higher than that of adenomas on
average49 (Fig. 1).
RATHKE CLEFT CYSTS
Rathke cleft cysts, like solid craniopharyngiomas, occur
along the craniopharyngeal duct and are felt to arise when
there is incomplete obliteration of the central embryonic cleft
separating the anterior lobe of the pituitary from the pars
intermedia. Rathke cleft cysts are differentiated from craniopharyngiomas by having single-layered walls of columnar or
cuboidal epithelium, often containing ciliated and goblet
cells.2,15 They are common lesions and usually asymptomatic,
reported incidentally in up to 33% of autopsy cases. Rathke
cleft cysts are 2 to 3 times more common in females than in
males.2,16 They can be seen at any age but, when symptomatic,
usually present between 40 and 60 years of age.2
Symptoms are more likely to be present when the cysts
are large enough to cause mass effect on adjacent structures
and are similar to symptoms observed with other sellar and
suprasellar masses.16,36 Rathke cleft cysts range in size from a
few millimeters to very large, in excess of 4.5 cm.15Y17 When
symptomatic, cysts can be treated with partial removal or cyst
aspiration, with a low rate of recurrence.
The primary imaging differential diagnosis is a cystic
craniopharyngioma. As with craniopharyngiomas, signal
intensities of the fluid in Rathke cleft cysts can be variable on
MRI, reflecting the heterogeneous composition of the fluid,
which ranges from serous to mucinous.2,15Y17 The cysts are
usually of higher T1 signal intensity than CSF, with the
majority being isointense to hyperintense to white matter,
probably reflecting the proteinaceous nature of the cyst
fluid.16,17 On T2-weighted imaging, Rathke cleft cysts demonstrate variable signal intensity; with high protein concentrations, there may be low signal intensity on T2-weighted images.
In contradistinction to the cysts of craniopharyngiomas, Rathke
cleft cysts usually demonstrate thin and uniform walls, and
enhancement of the walls is uncommon.2,16,17 Enhancement of
the walls of a Rathke cleft cyst may reflect inflammation or
infection. Wall calcification is uncommon.2
One group reported the presence of T1 hyperintense, T2
hypointense, nonenhancing intracystic nodules in 10 of 13
patients with pathologically confirmed Rathke cleft cysts,
corresponding to waxy, solid, intracystic masses intraoperatively, probably representing concretions of desquamated
cellular debris.18 They suggest that these nodules can be
distinguished from soft tissue nodules seen in craniopharyngiomas by their signal intensities and lack of enhancement (Fig. 2).
PITUITARY CARCINOMA
Pituitary carcinomas are extremely rare tumors, with
fewer than 150 cases reported.19 They are tumors of the
adenohypophysis that undergo discontinuous craniospinal or
systemic spread.19,20 In patients with pituitary carcinoma,
FIGURE 1. Craniopharyngioma. Coronal T2-weighted (A), unenhanced (B) and enhanced (C) coronal T1-weighted, and
enhanced sagittal T1-weighted MR images through the sella turcica demonstrate a multiloculated, mixed cystic, and solid
suprasellar mass. The walls of the mass enhance, and there are solid enhancing nodules (arrows) in the right anterolateral aspect of
the tumor (C). In this case, the mass is entirely suprasellar and can be easily distinguished from the normally enhancing pituitary
gland.
290
* 2005 Lippincott Williams & Wilkins
Tumors of the Pituitary and Sella Turcica
FIGURE 2. Rathke cleft cyst. Unenhanced sagittal (A) and coronal (B) T1-weighted, and enhanced coronal T1-weighted (C) MR
images demonstrate a well-circumscribed, nonenhancing, hyperintense intrasellar lesion, which displaces the normally enhancing
adenohypophysis superiorly (arrows). Enhanced sagittal T1-weighted MR image in a different patient (D) shows a thin enhancing
rim; note that the contents of the cyst are hyperintense to CSF and isointense to hyperintense relative to adjacent brain parenchyma.
47% have only systemic metastases, 40% have craniospinal
metastases, and 13% have both.20 Common sites of
hematogenous spread are the liver and bone; less common
reported sites include the lungs, lymph nodes, ovaries, heart,
pancreas, and myometrium.19,21 Craniospinal metastases
usually involve the cortex, cerebellum, and cerebellopontine
angles.19
The pathogenesis of pituitary carcinomas is not understood. It is likely that most develop secondary to transformation of an existing pituitary adenoma rather than develop de
novo.21 Most pituitary carcinomas are initially diagnosed as
invasive macroadenomas, and there is generally a latency
period of 5 to 10 years before finding metastases.19,21
Histologically, there are no reliable criteria for distinguishing
adenomas from pituitary carcinomas.20 A diagnosis of
pituitary carcinoma cannot be made without evidence of
distant spread.
There is no sex predilection, and pituitary carcinomas
can be seen in adults of any age (mean, 44 years).19,21
Approximately 75% of pituitary carcinomas are endocrinologically active; most are prolactin or adrenocorticotropic
hormoneYproducing tumors.20Y22
Clinical features of pituitary carcinoma are similar to
those of invasive adenomas, with symptoms due to mass
effect on surrounding structures or to the excessive hormone
production.19,21,22 A common clinical presentation is early
recurrence of tumor after resection, followed by a prolonged
course of repeated surgeries for local recurrences, before
metastatic disease.22 Once metastases are detected, the mean
survival time is 4 years; survival varies with endocrinologic
FIGURE 3. Pituitary carcinoma. Unenhanced sagittal T1-weighted (A) and enhanced coronal T1-weighted (B) MR images
demonstrate a bilobed sellar and suprasellar mass with heterogeneous enhancement. Note the circumferential Bwaisting^ that
occurs at the level of the diaphragma sella (arrows), which is commonly seen in pituitary macroadenomas. This mass is
radiographically indistinguishable from an adenoma.
291
Huang and Castillo
tumor subtypes, with adrenocorticotropic hormoneYproducing tumors having the worst prognosis.19 Patients with only
central nervous system (CNS) involvement seem to have
longer survival than those with systemic metastases.19
From a neuroimaging standpoint, distant spread is the
only feature which distinguishes pituitary carcinomas from
adenomas. With regard to the primary sellar tumor,
carcinomas cannot be differentiated from invasive macroadenomas.19,21 Like macroadenomas, pituitary carcinomas
appear as enhancing sellar masses with suprasellar/parasellar
extension and invasion of the cavernous sinus or bone. The
metastases of pituitary carcinoma are indistinguishable from
metastases of other carcinomas21 (Figs. 3 and 4).
GRANULAR CELL TUMORS
Granular cell tumors are rare and benign tumors of the
neurohypophysis and have also been referred to as choristomas, myoblastomas, and infundibulomas. They arise from
granular cellYtype pituicytes,31 but structurally identical
PITUITARY ASTROCYTOMAS
Astrocytomas arising from the pituitary gland are rare
and arise from the neurohypophysis. Astrocytomas of the
pilocytic type have been reported.23 In addition, there have
been several reports of low-grade neurohypophyseal glial
tumors, histologically distinct from pilocytic astrocytomas,
which have been referred to as pituicytomas.24Y29 Some
confusion in terminology has arisen as some authors have
used the term pituicytoma to encompass all astrocytomas
arising from the gland, whereas others consider the
pituicytoma to be a distinct entity.
The neurohypophysis contains specialized glial cells
referred to as Bpituicytes.^ Five different types of pituicytes
have been described,30 with most pituicytomas arising from
major and dark cell types.31 Pituicytomas are differentiated
from pilocytic astrocytomas by having plump, spindle-shaped
cells with a slightly fibrillar cytoplasm and by lack of Rosenthal
fibers, microcysts, and granular bodies found commonly in
pilocytic astrocytomas.24
Pituicytomas are seen from the third to ninth decades in
patients with a mean age of 40 years.24,28 There is a male
predominance.24,25,28 Pituicytomas may be entirely intrasellar or suprasellar or involve both compartments. Clinical
presentation is similar to that of other sellar and suprasellar
masses, with the most common presenting complaint being
hypopituitarism, followed by visual disturbances.28 Despite
the neurohypophyseal origin of these tumors, DI is not a
common presenting symptom.25,28 Total resection is usually
curative.25
Pituicytomas and pituitary pilocytic astrocytomas are
indistinguishable from one another radiographically and, in
general, cannot be distinguished from other neurohypophyseal tumors. Diagnosis of pituitary astrocytoma can only be
made pathologically. For the sake of simplicity, we refer to
pituitary tumors of glial origin as pituitary astrocytomas.
MRI features of pituitary astrocytomas are nonspecific
and are those of a solid, circumscribed, enhancing sellar or
suprasellar mass, usually isointense to gray matter on T1weighted and hyperintense on T2-weighted sequences.24,31,29
Anterior displacement of the normally enhancing adenohypophysis by the tumor may suggest that it is of neurohypophyseal origin.24 A pituitary astrocytoma containing solid and
cystic components has been reported, but the presence of
cysts is an uncommon feature.24
292
FIGURE 4. Pituitary carcinoma metastases. Enhanced sagittal
(A) and axial (B) T1-weighted MR images demonstrate
enhancing extraaxial, dural-based masses (arrows). The patient
had undergone resection of a prolactinoma in the past. Biopsy
of 1 of these lesions revealed metastatic prolactinoma.
The imaging appearance of granular cell tumors is
nonspecific, with an enhancing sellar or suprasellar mass seen
on MRI. Eleven percent of symptomatic granular cell tumors
are intrasellar, 42% are suprasellar, and 47% involve both
compartments.32 The masses are isointense to gray matter on
both T1- and T2-weighted sequences.32,37,35 Intense enhancement may be seen and reflects the high vascularity of these
tumors. Calcifications may be present. Absence of the normal
pituitary bright spot may be a clue that the tumor is of
neurohypophyseal origin, but this finding is nonspecific, as
the posterior pituitary bright spot may be absent in 10% to
20% of normal subjects38 (Fig. 5).
GANGLIOCYTOMAS
FIGURE 5. Granular cell tumor. Unenhanced (A) and
enhanced (B) coronal T1-weighted MR images through the
pituitary demonstrate a well-circumscribed, enhancing nodule
arising from the pituitary stalk.
tumors have been described elsewhere in the CNS.32 They are
the most common primary tumor of the neurohypophysis33
and are seen in up to 17% of nonselected adult autopsies.34
The tumors are twice as common in females than in males.32
Granular cell tumors are usually asymptomatic but,
when symptomatic, usually present in the fifth decade.32,35 As
with other nonfunctional pituitary tumors, symptoms are
primarily related to size and mass effect. Tumors are usually
very large when discovered.32,35 Approximately 90% of
symptomatic patients have visual complaints, and 50% have
clinical or laboratory signs of hypopituitarism or hyperprolactinemia.32 Headache is a common complaint. Treatment
for symptomatic granular cell tumors is surgical; postoperative radiation is controversial but appears to increase
mean survival time and time to recurrence after surgery.32,37
Although the pituitary gland does not contain neurons,
a small number of reports of pituitary tumors composed at
least partly of ganglion cells can be found in the literature.
These tumors are referred to as gangliocytomas. The exact
histogenesis of these tumors is debated, with some authors
suggesting that they arise from embryonal pituitary cell rests
that have features between neurons and adenohypophyseal
cells and others suggesting a common hypothalamic origin.39
The tumors are found in adults and are more common in
females.40
Although these tumors may consist exclusively of
ganglion cells, the majority (65%Y76%) of gangliocytomas
are found in association with adenomas.39Y41 Because of this,
some suggest the name, mixed gangliocytoma-adenoma
(MGA).42 Approximately 75% of patients with pituitary
gangliocytomas demonstrate pituitary hormone hypersecretion,
with oversecretion of growth hormone being the most common
manifestation, followed by Cushing disease.40,41 Interestingly,
the MGAs are more likely to be hormonally active than the pure
gangliocytomas.40 In addition to the endocrine abnormalities
seen with MGAs, visual changes and headaches can also
occur.39
On MRI, intrasellar gangliocytomas and MGAs may
not be distinguishable from pituitary macroadenomas and
appear as an enhancing sellar and suprasellar mass. Some
have noted that the suprasellar portion of an MGA tends to be
more spherical than macroadenomas and that they do not
demonstrate the waist at the level of the diaphragma sella that
macroadenomas do42 (Fig. 6).
MENINGIOMAS
Meningiomas can originate from any dural surface,
including the tuberculum sella, olfactory groove, sphenoid
wing, diaphragma sella, and sella turcica.2 They account for
approximately 20% of all intracranial neoplasms; are tumors
of adults, increasing in incidence with increasing age (peak
incidence, 60Y70 years); and are 2 times more common in
females.2,43 Whereas 10% to 15% of meningiomas arise in
the parasellar region, purely intrasellar meningiomas are
rare.2,44 The majority of intrasellar meningiomas arise from
the undersurface of the diaphragma sella, but meningiomas
originating from the floor or walls of the sella have been
reported.44
293
Huang and Castillo
Meningiomas are benign, slow-growing tumors. Intrasellar meningiomas may mimic nonfunctioning adenomas in
their clinical presentation, with primary symptoms being
headache, visual disturbances, visual field defects, and
endocrinologic abnormalities (hypopituitarism or hyperprolactinemia).44Y46 Cases of an intrasellar meningioma
mimicking pituitary apoplexy have been reported.46,47
Although benign, meningiomas can be locally aggressive and
recur after incomplete resection. Encasement and, ultimately,
occlusion of an internal carotid artery can occur.2
Preoperative diagnosis of an intrasellar meningioma is
extremely useful in surgical planning and may sway surgeons
away from the transsphenoidal approach used for most
adenomas in favor of a transcranial approach.47Y49 The high
degree of vascularity of most meningiomas predisposes to
excessive intraoperative bleeding during resection, which is
generally more easily controlled from a transcranial approach.
Because of the vascularity of meningiomas, preoperative
embolization of tumors is advocated by some as being helpful
in reducing intraoperative blood loss.44 Diaphragma sella
meningiomas are typically supplied by arteries of the
ophthalmic segment of the internal carotid arteries.45
Purely intrasellar meningiomas can be extremely
difficult to distinguish from adenomas by imaging.45,48
Intrasellar meningiomas typically appear as masses which
are hypointense to isointense to gray matter on both T1- and
T2-weighted sequences.2,7 Sellar enlargement is common.44,45,48 Enhancement after administration of gadolinium
is marked and homogeneous, with homogeneous enhance-
ment seen in more than 90%.7,50 The rate of enhancement is
usually rapid.51 The enhancement profile of meningiomas
may aid in distinguishing them from adenomas, as adenomas
generally enhance less intensely and more heterogeneously
than meningiomas and demonstrate a longer time-to-peak
enhancement on dynamic imaging.7,50,51 The presence of
an enhancing dural tail is not a feature of intrasellar
meningiomas.45,52
Identification of the pituitary gland as separate from a
sellar mass is probably the single most useful finding in
differentiating adenomas from sellar meningiomas. Visualization of a CSF cleft between a tumor and the gland, although
uncommon, virtually excludes the diagnosis of adenoma.7,53
Another finding which may favor meningioma is hyperostosis
of the floor of the sella or adjacent bony structures, seen in
34% of sellar meningiomas.7,51 Prominent vessels may be
seen in approximately 65% of sellar meningiomas.7 Macroscopically detectable calcifications are uncommon and are
seen in just over 10% of sellar meningiomas7,44 (Fig. 7).
GERM CELL TUMORS
Intracranial germ cell tumors are rare malignant
tumors, representing only 0.1% to 2% of all primary brain
neoplasms. They are believed to arise from totipotent germ
cells that fail to migrate to the genital crest during embryonic
life. Primarily midline tumors, germ cell tumors are
subdivided into teratomas, germinomas, embryonal cell
carcinoma, choriocarcinoma, endodermal sinus (yolk sac)
tumors, and mixed germ cell tumors. Pure germinomas
FIGURE 6. Gangliocytoma. Coronal T2-weighted (A) and enhanced sagittal T1-weighted (B) MR images demonstrate a
heterogeneous, enhancing sellar and suprasellar mass. Note the spherical configuration of the mass and the absence of a Bwaist^ at
the level of the diaphragma sella.
294
account for two thirds of intracranial germ cell tumors, with
nongerminomatous mixed germ cell tumors accounting for
most of the rest.54
Germ cell tumors are primarily tumors of childhood,
with a peak presentation at 10 to 12 years. Pure germinomas
occur at an older age than nongerminomatous tumors.54 The
majority of intracranial germ cell tumors are found in the
pineal or suprasellar regions. Intracranial germ cell tumors
occur twice as often in males than females, but this male
predominance is limited to tumors arising in the pineal
region. Suprasellar germ cell tumors occur slightly more
frequently in females.55,56 Pure germinomas are radiosensitive and carry a favorable prognosis. More than 90%
of germinomas can be treated effectively with radiation.
Prognosis for patients with nongerminomatous tumors is less
favorable, with only 40% to 60% demonstrating disease
control with radiation therapy alone.55
Primarily intrasellar germinomas are rare and have a
female predominance.57 Most suprasellar germinomas originate either in the floor of the third ventricle or in the
infundibulum. It is felt that intrasellar germinomas represent
infundibular tumors with primarily intrasellar growth.57
Patients most commonly present with endocrine abnormalities, with DI being the most common symptom to prompt
patients to seek medical attention.57,58 Development of DI is
related to invasion or compression of the posterior lobe or
infundibulum and may persist for years before a diagnosis is
made. Other manifestations include hypopituitarism in
children and adolescents and hypogonadism in adults.57
Hyperprolactinemia and precocious puberty have been
observed.57,59 Large tumors and primarily suprasellar tumors
may present with visual changes or oculomotor palsies. 58,59
Serum tumor markers can be extremely useful in
establishing the diagnosis of a germ cell tumor. Production of
either >-fetoprotein (AFP) or A-human chorionic gonadotropin (BHCG) can be seen in a number of subtypes of germ
cell tumors. Tumors with a yolk sac component secrete AFP.
Choriocarcinomas produce high levels of BHCG. Patients
with pure germinomas can secrete BHCG into the CSF at low
levels, and this is considered an early indication of CSF
dissemination. Because other intracranial tumors do not
produce AFP or BHCG, the presence of these markers in CSF
or serum in the setting of an intracranial tumor is essentially
diagnostic of a germ cell tumor.54,55
Because intracranial germ cell tumors have a predilection to disseminate via CSF, MRI of the entire craniospinal
axis and lumbar puncture for cytology are mandatory.54 MRI
cannot reliably differentiate the different types of germ cell
tumors. The earliest finding in cases of neurohypophyseal
germ cell tumors is probably absence of the normal posterior
lobe bright spot on T1-weighted images. This can be followed
by swelling of the stalk and subsequent mass formation,
which may displace the enhancing pituitary gland anteriorly.
Loss of the normal pituitary bright spot and thickening of the
stalk are also seen with idiopathic DI, granulomatous
processes, and lymphocytic hypophysitis. Because of this,
some have proposed serial MRI and endocrinologic evaluations in patients presenting with DI and loss of the posterior
bright spot without a definite mass.60
FIGURE 7. Meningioma. Enhanced coronal T1-weighted MR
image demonstrates a sellar and suprasellar mass with marked
enhancement.
Larger sellar/suprasellar germ cell tumors have a
nonspecific imaging appearance and usually cannot be
distinguished from other tumors. The MR findings are those
of an enhancing solid sellar mass, with or without suprasellar
extension. Cysts and calcifications may be seen.61 Differential
enhancement of the tumor and the enhancing displaced
anterior lobe may aid in distinguishing these tumors from
adenomas.60,62 Although rare, cavernous sinus invasion has
been reported to occur with larger tumors58 (Fig. 8).
LYMPHOMA
CNS lymphoma may be primary or metastatic. Less
than 1% of metastases to the pituitary are secondary to
lymphoma.63 Primary CNS lymphoma refers to disease
limited to the craniospinal axis, without systemic disease.64
It represents up to 2% of all primary CNS malignancies and is
practically always of the non-Hodgkin type, with the majority
being B-cell lymphoma.65 The incidence of CNS lymphoma
has more than tripled in the United States since the early
1980s,66 due to the increase in number of immunocompromised individuals. In patients with AIDS, primary CNS
lymphoma makes up 3% of intracranial neoplasms. Interestingly, the incidence of primary CNS lymphoma has also been
increasing in the nonimmunocompromised population.64,66,67
Primary CNS lymphoma is considered by the US Centers for
Disease Control to be an AIDS-defining illness in those
infected with HIV. The mean age at presentation is
significantly lower for immunocompromised patients (mean
age, 30Y40 years) versus immunocompetent patients (mean
age, 60Y70 years); males are more frequently affected. There
does not appear to be a sex predilection in the immunocompetent population.65
Primary lymphoma arising in the sella is exceedingly
rare, with only a handful of cases reported.68Y74 Patients range
295
Huang and Castillo
in age from 44 to 86 years. Presenting symptoms are not
specific and include headaches, hypopituitarism, visual field
deficits, and oculomotor palsies.
The imaging appearances of primary CNS lymphoma
tend to differ based on whether patients have normal or
suppressed immunity. CNS lymphoma in patients with
normal immune systems usually appears as a solitary mass
with intermediate to low signal intensity relative to gray
matter on both T1- and T2-weighted sequences; enhancement
with gadolinium is seen in nearly all cases and is homogenous
in approximately three quarters of cases.75,65 The relative
lack of T2 prolongation in CNS lymphoma is generally
attributed to dense cellularity and to a high nuclearcytoplasmic ratio and may be helpful in distinguishing
lymphoma from other CNS tumors; unfortunately, this
finding is relatively insensitive, as it is seen in just over
50% of cases.65 Calcification and hemorrhage in CNS
lymphoma are rare.75
In immunocompromised patients, lesions of CNS
lymphoma are likely to be multiple and to demonstrate
necrosis.65 In the setting of necrosis, the center of the lesion is
T2 hyperintense, whereas the periphery remains of intermediate to low signal.75 Contrast enhancement is heterogeneous in this population, and rim enhancement is more
common.65,75
MRI characteristics of sellar lymphomas are largely
nonspecific, with most cases appearing as homogeneously or
heterogeneously enhancing sellar masses.70,72Y74 Isointensity
to hypointensity of masses relative to gray matter on T2weighted imaging has been reported in sellar lymphoma70,74
and may be helpful in distinguishing it from pituitary
adenoma.
METASTASES
FIGURE 8. Germ cell tumor. Unenhanced (A) and enhanced
(B) sagittal T1-weighted images demonstrate a bilobed sellar
and suprasellar mass with heterogeneous enhancement.
Cysts are present within the mass.
296
Metastases to the pituitary gland and sella are
uncommon. In surgical series examining patients undergoing
transsphenoidal surgery for sellar or parasellar tumors,
metastases are found in less than 1% of cases.63 In autopsy
series, evidence of metastases to the pituitary is seen in
approximately 5% of patients with known malignancy. In
approximately two thirds of these cases, the pituitary is
macroscopically normal.75 The most common primary
malignancies to metastasize to the pituitary gland are breast
and lung cancers which together account for more than 60%
of all pituitary metastases.63,76 In 1 review, metastases to the
pituitary were found in 17.6% of autopsies of patients with
breast cancer.63 Although breast and lung cancers are the
most common primaries to metastasize to the pituitary,
metastases from tumors of nearly every tissue type have been
reported.63
Metastases can reach the sella turcica via hematogenous spread, spread from a hypothalamic or hypophyseal
metastasis through portal vessels, direct extension from skull
base tumors, or meningeal spread.63 Hematogenous metastases to the pituitary have a predilection to involve the
posterior lobe. In 1 review of 201 cases of pituitary
metastases, the posterior lobe alone was involved in 50.8%
of cases, both lobes were involved in approximately 33.8% of
cases, and the anterior lobe was involved in 15.4% of cases.77
The relative infrequency of metastases exclusive to the
anterior lobe has been attributed to its lack of a direct arterial
blood supply.2,63 It is hypothesized that the first capillary bed
of the portal system may trap metastases before they can
travel to the anterior lobe.2 Therefore, metastatic involvement
of the adenohypophysis is more often due to contiguous
field deficits, anterior pituitary insufficiency, oculomotor
palsies, and headache.63,76
Imaging features of pituitary metastases are variable,
and in the absence of coexistent brain metastases, differentiation from an adenoma is difficult. On MRI, pituitary
metastases appear as sellar or suprasellar masses which
often are isointense or hypointense to gray matter on T1weighted images and are usually of increased T2 signal. They
enhance after gadolinium administration. Enhancement may
be homogeneous or heterogeneous, and rim enhancement can
also be seen.2,63 Like macroadenomas, metastases can appear
as dumbbell-shaped intrasellar and suprasellar tumors.
Invasion of the cavernous sinus and underlying sphenoid
sinus may be seen.63 Loss of the normal posterior bright spot
FIGURE 9. Metastasis. Coronal T2-weighted (A) and
unenhanced (B) and enhanced (C) coronal T1-weighted
images through the sella demonstrate a predominantly rim
enhancing sellar mass with suprasellar extension. Central areas
of T1 hyperintensity in B and T2 hypointensity in A probably
reflect hemorrhage. The mass displaces the optic chiasm
superiorly. This was a metastasis from breast cancer.
spread from the posterior lobe than to direct hematogenous
spread.78
Probably because of the predilection for metastases to
involve the posterior lobe, the most common symptom
observed in patients with pituitary metastases is DI, which
occurs in 45% of cases.63 Other signs/symptoms include visual
FIGURE 10. Melanoma metastasis. Unenhanced sagittal
T1-weighted (A) and coronal T2-weighted (B) MR images
demonstrate a sellar mass which is markedly hyperintense on
the T1-weighted image and hypointense on the T2-weighted
image relative to adjacent brain parenchyma. The signal
characteristics presumably are due to the presence of melanin.
297
Huang and Castillo
has been reported.79 Rapid growth of tumor, infundibular
enlargement, and apparent destruction rather than remodeling
of the bone of the sella turcica have also been reported and
may favor metastasis over adenoma2,79,80 (Figs. 9 and 10).
CONCLUSION
Differentiating pituitary adenomas from any of the
above entities can be extremely difficult and, at times, even
impossible. In some patients, however, there are specific
imaging findings which, when present and when correlated
with appropriate clinical information, can lead the radiologist
to make the diagnosis or at least to suggest the actual
diagnosis.
REFERENCES
1. Sautner D, Saeger W, Ludecke DK. Tumors of the sellar region
mimicking pituitary adenomas. Exp Clin Endocrinol. 1993;
101(5):283Y289.
2. FitzPatrick M, Tartaglino LM, Hollander MD, et al. Imaging of sellar
and parasellar pathology. Radiol Clin North Am. January
1999;37(1):101Y121.
3. Karavitaki N, Brufani C, Warner JT, et al. Craniopharyngiomas in
children and adults: systematic analysis of 121 cases with long-term
follow-up. Clin Endocrinol (Oxf). April 2005;62(4):397Y409.
4. Bunin GR, Surawicz TS, Witman PA, et al. The descriptive
epidemiology of craniopharyngioma. J Neurosurg. October 1998;
89(4):547Y551.
5. Zimmerman RA. Imaging of intrasellar, suprasellar, and parasellar
tumors. Semin Roentgenol. April 1990;25(2):174Y197.
6. Lafferty AR, Chrousos GP. Pituitary tumors in children and adolescents.
J Clin Endocrinol Metab. December 1999;84(12):4317Y4323.
7. Donovan JL, Nesbit GM. Distinction of masses involving the sella and
suprasellar space: specificity of imaging features. AJR Am J Roentgenol.
September 1996;167(3):597Y603.
8. Hershey BL. Suprasellar masses: diagnosis and differential diagnosis.
Semin Ultrasound CT MR. June 1993;14(3):215Y231.
9. Crotty TB, Scheithauer BW, Young WF Jr, et al. Papillary
craniopharyngioma: a clinicopathological study of 48 cases.
J Neurosurg. August 1995;83(2):206Y214.
10. Sklar CA. Craniopharyngioma: endocrine abnormalities at presentation.
Pediatr Neurosurg. 1994;21(suppl 1):18Y20.
11. Young SC, Zimmerman RA, Nowell MA, et al. Giant cystic
craniopharyngiomas. Neuroradiology. 1987;29(5):468Y473.
12. Ahmadi J, Destian S, Apuzzo ML, et al. Cystic fluid in
craniopharyngiomas: MRI and quantitative analysis. Radiology.
March 1992;182(3):783Y785.
13. Hald JK, Eldevik OP, Skalpe IO. Craniopharyngioma identification by
CT and MRI at 1.5 T. Acta Radiol. March 1995;36(2):142Y147.
14. Curran JG, O’Connor E. Imaging of craniopharyngioma. Childs Nerv
Syst. August 2005;21(8-9):635Y639.
15. Kucharczyk W, Peck WW, Kelly WM, et al. Rathke cleft cysts: CT,
MRI, and pathologic features. Radiology. November
1987;165(2):491Y495.
16. Ross DA, Norman D, Wilson CB. Radiologic characteristics and results
of surgical management of Rathke’s cysts in 43 patients. Neurosurgery.
February 1992;30(2):173Y178.
17. Tominaga JY, Higano S, Takahashi S. Characteristics of Rathke’s cleft
cyst in MRI. Magn Reson Med Sci. April 2003;2(1):1Y8.
18. Byun WM, Kim OL, Kim D. MRI findings of Rathke’s cleft cysts:
significance of intracystic nodules. AJNR Am J Neuroradiol. March
2000;21(3):485Y488.
19. Kaltsas GA, Nomikos P, Kontogeorgos G, et al. Clinical review:
diagnosis and management of pituitary carcinomas. J Clin Endocrinol
Metab. May 2005;90(5):3089Y3099.
20. Pernicone PJ, Scheithauer BW, Sebo TJ, et al. Pituitary carcinoma: a
clinicopathologic study of 15 cases. Cancer. February 15, 1997;
79(4):804Y812.
298
21. Scheithauer BW, Kurtkaya-Yapicier O, Kovacs KT, et al. Pituitary
carcinoma: a clinicopathological review. Neurosurgery. May 2005;
56(5):1066Y1074.
22. Kaltsas GA, Grossman AB. Malignant pituitary tumours. Pituitary.
April 1998;1(1):69Y81.
23. Rossi ML, Bevan JS, Esiri MM, et al. Pituicytoma (pilocytic
astrocytoma). Case report. J Neurosurg. November 1987;67(5):768Y772.
24. Brat DJ, Scheithauer BW, Staugaitis SM, et al. Pituicytoma: a distinctive
low-grade glioma of the neurohypophysis. Am J Surg Pathol.
March 2000;24(3):362Y368.
25. Figarella-Branger D, Dufour H, Fernandez C, et al. Pituicytomas,
a mis-diagnosed benign tumor of the neurohypophysis: report of three
cases. Acta Neuropathol (Berl). September 2002;104(3):313Y319.
26. Hurley TR, D’Angelo CM, Clasen RA, et al. Magnetic resonance
imaging and pathological analysis of a pituicytoma: case report.
Neurosurgery. August 1994;35(2):314Y317.
27. Katsuta T, Inoue T, Nakagaki H, et al. Distinctions between pituicytoma
and ordinary pilocytic astrocytoma. Case report. J Neurosurg.
February 2003;98(2):404Y406.
28. Takei H, Goodman JC, Tanaka S, et al. Pituicytoma incidentally found at
autopsy. Pathol Int. November 2005;55(11):745Y749.
29. Uesaka T, Miyazono M, Nishio S, et al. Astrocytoma of the pituitary
gland (pituicytoma): case report. Neuroradiology. February
2002;44(2):123Y125.
30. Takei Y, Seyama S, Pearl GS, et al. Ultrastructural study of the human
neurohypophysis. II. Cellular elements of neural parenchyma, the
pituicytes. Cell Tissue Res. 1980;205(2):273Y287.
31. Shah B, Lipper MH, Laws ER, et al. Posterior pituitary astrocytoma: a
rare tumor of the neurohypophysis: a case report. AJNR Am J
Neuroradiol. August 2005;26(7):1858Y1861.
32. Schaller B, Kirsch E, Tolnay M, et al. Symptomatic granular cell tumor
of the pituitary gland: case report and review of the literature.
Neurosurgery. January 1998;42(1):166Y170.
33. Liwnicz BH, Liwnicz RG, Huff JS, et al. Giant granular cell tumor of the
suprasellar area: immunocytochemical and electron microscopic studies.
Neurosurgery. August 1984;15(2):246Y251.
34. Barrande G, Kujas M, Gancel A, et al. Granular cell tumors. Rare tumors of
the neurohypophysis. Presse Med. October 14, 1995;24(30):1376Y1380.
35. Iglesias A, Arias M, Brasa J, et al. MRI findings in granular cell tumor of
the neurohypophysis: a difficult preoperative diagnosis. Eur Radiol.
2000;10(12):1871Y1873.
36. Teears RJ, Silverman EM. Clinicopathologic review of 88 cases of
carcinoma metastatic to the putuitary gland. Cancer. July 1975;
36(1):216Y220.
37. Buhl R, Hugo HH, Hempelmann RG, et al. Granular-cell tumour: a rare
suprasellar mass. Neuroradiology. April 2001;43(4):309Y312.
38. Elster AD. Imaging of the sella: anatomy and pathology. Semin
Ultrasound CT MR. June 1993;14(3):182Y194.
39. Geddes JF, Jansen GH, Robinson SF, et al. FGangliocytomas` of the
pituitary: a heterogeneous group of lesions with differing histogenesis.
Am J Surg Pathol. April 2000;24(4):607Y613.
40. Towfighi J, Salam MM, McLendon RE, et al. Ganglion cell-containing
tumors of the pituitary gland. Arch Pathol Lab Med. April 1996;
120(4):369Y377.
41. Puchner MJ, Ludecke DK, Saeger W, et al. Gangliocytomas of
the sellar regionVa review. Exp Clin Endocrinol Diabetes.
1995;103(3):129Y149.
42. Castillo M, Mukherji SK. Intrasellar mixed gangliocytoma-adenoma.
AJR Am J Roentgenol. October 1997;169(4):1199Y1200.
43. Bondy M, Ligon BL. Epidemiology and etiology of intracranial
meningiomas: a review. J Neurooncol. September 1996;29(3):197Y205.
44. Nozaki K, Nagata I, Yoshida K, et al. Intrasellar meningioma: case report
and review of the literature. Surg Neurol. May 1997;47(5):447Y452.
[discussion 452-4].
45. Kinjo T, al-Mefty O, Ciric I. Diaphragma sellae meningiomas.
Neurosurgery. June 1995;36(6):1082Y1092.
46. Kudo H, Takaishi Y, Minami H, et al. Intrasellar meningioma
mimicking pituitary apoplexy: case report. Surg Neurol. October 1997;
48(4):374Y381.
47. Orakdogeny M, Karadereler S, Berkman Z, et al. Intra-suprasellar
meningioma mimicking pituitary apoplexy. Acta Neurochir (Wien).
May 2004;146(5):511Y515.
48. Cappabianca P, Cirillo S, Alfieri A, et al. Pituitary macroadenoma and
diaphragma sellae meningioma: differential diagnosis on MRI.
Neuroradiology. January 1999;41(1):22Y26.
49. Yamasaki F, Kurisu K, Satoh K, et al. Apparent diffusion coefficient of
human brain tumors at MRI. Radiology. June 2005;235(3):985Y991.
50. Michael AS, Paige ML. MRI of intrasellar meningiomas simulating
pituitary adenomas. J Comput Assist Tomogr. November-December
1988;12(6):944Y946.
51. Satoh H, Arita K, Kurisu K, et al. Intrasellar meningioma: characteristic
imaging findings. Neuroradiology. May 1996;38(4):328Y329.
52. Taylor SL, Barakos JA, Harsh GR 4th, et al. Magnetic resonance
imaging of tuberculum sellae meningiomas: preventing preoperative
misdiagnosis as pituitary macroadenoma. Neurosurgery. October
1992;31(4):621Y627.
53. Yeakley JW, Kulkarni MV, McArdle CB, et al. High-resolution MRI of
juxtasellar meningiomas with CT and angiographic correlation. AJNR
Am J Neuroradiol. March-April 1988;9(2):279Y285.
54. Hooda BS, Finlay JL. Recent advances in the diagnosis and treatment of
central nervous system germ-cell tumours. Curr Opin Neurol. December
1999;12(6):693Y696.
55. Packer RJ, Cohen BH, Cooney K. Intracranial germ cell tumors.
Oncologist. 2000;5(4):312Y320.
56. Takeuchi J, Handa H, Nagata I. Suprasellar germinoma. J Neurosurg.
July 1978;49(1):41Y48.
57. Frank G, Galassi E, Fabrizi AP, et al. Primary intrasellar germinoma:
case report. Neurosurgery. May 1992;30(5):786Y788.
58. Endo T, Kumabe T, Ikeda H, et al. Neurohypophyseal germinoma
histologically misidentified as granulomatous hypophysitis. Acta
Neurochir (Wien). November 2002;144(11):1233Y1237.
59. Cho DY, Wang YC, Ho WL. Primary intrasellar mixed germ-cell tumor
with precocious puberty and diabetes insipidus. Childs Nerv Syst.
January 1997;13(1):42Y46.
60. Oishi M, Morii K, Okazaki H, et al. Neurohypophyseal germinoma
traced from its earliest stage via magnetic resonance imaging: case
report. Surg Neurol. October 2001;56(4):236Y241.
61. Greiner FG, Takhtani D. Neuroradiology case of the day. Malignant
mixed germ cell tumor with yolk sac and teratomatous components.
Radiographics. May-June 1999;19(3):826Y829.
62. Sumida M, Uozumi T, Kiya K, et al. MRI of intracranial germ cell
tumours. Neuroradiology. January 1995;37(1):32Y37.
63. Komninos J, Vlassopoulou V, Protopapa D, et al. Tumors metastatic to
the pituitary gland: case report and literature review. J Clin Endocrinol
Metab. February 2004;89(2):574Y580.
64. Fine HA, Mayer RJ. Primary central nervous system lymphoma. Ann
Intern Med. December 1, 1993;119(11):1093Y1104.
65. Johnson BA, Fram EK, Johnson PC, et al. The variable MR appearance
of primary lymphoma of the central nervous system: comparison with
histopathologic features. AJNR Am J Neuroradiol. March 1997;
18(3):563Y572.
66. Jellinger KA, Paulus W. Primary central nervous system lymphomasVan
update. J Cancer Res Clin Oncol. 1992;119(1):7Y27.
67. Maher EA, Fine HA. Primary CNS lymphoma. Semin Oncol. June 1999;
26(3):346Y356.
68. Au WY, Kwong YL, Shek TW, et al. Diffuse large-cell B-cell lymphoma
in a pituitary adenoma: an unusual cause of pituitary apoplexy. Am J
Hematol. April 2000;63(4):231Y232.
69. Gottfredsson M, Oury TD, Bernstein C, et al. Lymphoma of the pituitary
gland: an unusual presentation of central nervous system lymphoma in
AIDS. Am J Med. November 1996;101(5):563Y564.
70. Kaufmann TJ, Lopes MB, Laws ER Jr, et al. Primary sellar lymphoma:
radiologic and pathologic findings in two patients. AJNR Am J
Neuroradiol. March 2002;23(3):364Y367.
71. Kuhn D, Buchfelder M, Brabletz T, et al. Intrasellar malignant
lymphoma developing within pituitary adenoma. Acta Neuropathol
(Berl). March 1999;97(3):311Y316.
72. Landman RE, Wardlaw SL, McConnell RJ, et al. Pituitary lymphoma
presenting as fever of unknown origin. J Clin Endocrinol Metab.
April 2001;86(4):1470Y1476.
73. Mathiasen RA, Jarrahy R, Cha ST, et al. Pituitary lymphoma: a case
report and literature review. Pituitary. May 2000;2(4):283Y287.
74. Singh S, Cherian RS, George B, et al. Unusual extra-axial central
nervous system involvement of non-Hodgkin’s lymphoma: magnetic
resonance imaging. Australas Radiol. February 2000;44(1):112Y114.
75. Erdag N, Bhorade RM, Alberico RA, et al. Primary lymphoma
of the central nervous system: typical and atypical CT and MRI
appearances. AJR Am J Roentgenol. May 2001;176(5):1319Y1326.
76. Weilbaecher C, Patwardhan RV, Fowler M, et al. Metastatic lesions
involving the sella: report of three cases and review of the literature.
Neurol India. September 2004;52(3):365Y368.
77. McCormick PC, Post KD, Kandji AD, et al. Metastatic carcinoma to the
pituitary gland. Br J Neurosurg. 1989;3(1):71Y79.
78. Leramo OB, Booth JD, Zinman B, et al. Hyperprolactinemia,
hypopituitarism, and chiasmal compression due to carcinoma metastatic
to the pituitary. Neurosurgery. April 1981;8(4):477Y480.
79. Koshimoto Y, Maeda M, Naiki H, et al. MR of pituitary metastasis in a
patient with diabetes insipidus. AJNR Am J Neuroradiol. April
1995;16(suppl 4):971Y974.
80. Schubiger O, Haller D. Metastases to the pituitary-hypothalamic axis. An
MR study of 7 symptomatic patients. Neuroradiology. 1992;
34(2):131Y134.
299

Nonadenomatous Tumors of the Pituitary and Sella Turcica

Transcription

Similar documents

ESPECTROSCOPIA DE PRÓTONS POR RESSONÂNCIA

pituitary tumors - University of Rochester Medical Center

Differential Diagnosis of Sellar Lesions

Pituitary Tumors - American Brain Tumor Association

LH-R FSH-R

Carcinoid Tumors of the Rectum Silver Reactions, Fluorescence

An Interpretation Of Michelangelo`s Creation Of Adam

MALE GENITAL SYSTEM

hypopituitarism - Pituitary Society

Meningioma - Gruppo Otologico

Hypothalamus: Functions

Figure 1: Left Ear Glomus Tumors (Paraganglioma) Glomus tumor

Glomus Tumors of the Temporal Bone

Lecture 16 Urinary/Endocrine Systems

Case 2 - Weill Cornell Dermatopathology Service

Plasticity between Epithelial and Mesenchymal

Revista Mexicana de Neurociencia

Feline Lymphoma.

Mucous Retention Cyst!

copyrighted material - beck

Casciato, Lowitz