Pineal region masses: differential diagnosis.

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Pmeal
Region
Masses
Differential
:
#{149}
Diagnosis
James
G. Smirniotopoulos,
Hernando
Mena,
LTC,
Most
young
pineal
male
neous
mass
with
signal
the
mass
engulfs
matter;
tilocular
region
patients.
masses
bryonal
or
be seen
histologic
in patients
diagnosis
phologic
logic
have
verification
neoplastic.
U
INTRODUCTION
pineal
region
is a central
cisterns
ventricle;
of the
and the
overlying
occur
splenium
in this
area
ofchildhood
occurrence
terms:
(krm
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Pineal
From
ccli
c
opinions
RSNA.
pmneal
location
corpus
that
and
the
Institute
147.3629
Pincal
the
of all intracranial
CSF
lxdy.
that
pineal
=
Pincal
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to
gland;
the
the
poste-
thalami,
and
lesions
and
that
about
4%
States
(1). However,
the
the reported
rate cx-
cc-rcbrospinal
1-17.1346
few
histo-
appear
various
masses
in the United
in Asia, where
of Pathology,
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masses
Combined,
1%-3%
Thus,
and velum
interpositum;
of the brain
stem,
the
callosum.
than
very
pattern.
the
may
the correct
of the mor-
characteristics,
includes
calcifiand
Although
evaluation
region
plate
tissues
pineal
fluid
body.
CT.
147.121
1
Pincal
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body.
MR.
147.3621
of Radiologic
Md (J.G.S.);
or as reflecting
ncoplasm.
DC 20306-6000
and
DC (J.G.S.).
Receivedjanuary
Address
reprint
requests
The
intensity
empineo-
12:577-596
I)cpartmcnt
Washington,
Bethesda.
Forces
or older.
a careful
mul-
and
either
predilection
imaging
most
midline
less
neoplasms,
1992;
the
Sts,
signal
quadrigemmnal
adjacent
solid
of the
Armed
=
body.
RadioGraphics
I
for
represent
AFIP
147.1214
and
intracranial
masses
encountered
of pineal
masses
is notably
higher
Abbreviations:
Index
of age
with
sexual
are
of pineal
tumor,
usually
preexisting
no
of gray
types
sinus
are
“explode”
have
pathognomonic
is necessary
be
may
that
occur
in
is a homoge-
Teratomas
Other
endodermal
20 years
suggested
a truly
areas.
neoplasms
they
are
be
USN
to those
gland.
lipid
parenchymal
attenuation,
tumors
surrounding
nor
third
containing
which
MC,
similar
pineal
choriocarcinoma,
who
may
features,
of these
attenuation
calcified
gei-minomas,
LCDR,
germ
cell neoplasms
is a germinoma,
which
and
pineoblastomas,
the
Rushing
malignant
common
a densely
Pineal
Unlike
the
are
most
intensity
include
cations.
#{149}
ElisabetbJ.
masses
carcinoma.
cytomas
Fern
masses
The
heterogeneous
region
The
MD
USA
MC,
assertions
views
the
Pathology.
(J.G.S..
E)epartments
Forces
H.M.);
ofRadiology
2, 1992;
toJ.G.S.
revision
contained
herein
of the
Armed
E.J.R.,
Departments
Institute
the
and
Neurology.
requestedJanuary
are
of the
the
views
or the
Navy
Bldg
Services
received
of the
or the
authors
Rm M- 1 2 1. Ala.ska
54
Universityofthc
Georgetown
30 and
private
Army
of Pathology,
Uniformed
Health
University
February
and
Department
are
Hospital.
11: accepted
not
to he construed
and
Sciences,
Washington.
February
14.
as official
of Defense.
1992
577
ceeds
of the
9% of all intracranial
neoplasms
seen here
unique
to this
tinctly
uncommon
tumor
to the
a limited
region
list.
U
NORMAL
of the
brain
elsewhere.
pineal
and
tic
masses
(1).
are peculiar
and
are
dis-
Localizing
region
yet
Most
or
allows
accurate
a
one
differential
ANATOMY,
to offer
scan
diagnos-
quadrigeminal
plate cistern
is a U-shaped
structure
that surrounds
the pineal
gland
and
the dorsal
brain
stem and has attenuation
equal
to that ofCSF.
However,
on MR and CT
images
obtained
in a true horizontal
plane,
the quadrigeminal
plate cistern
is a triangle
pointing
posteriorly,
with its base against
the
tectal
plate.
The adjacent
fluid-filled
spaces
provide
good
imaging
contrast
on both Tiweighted
MR images
and CT scans
(Fig 1).
Another
important
anatomic
landmark
of
the pineal
region
is the pair ofvessels
imrnediately above
the pineal
gland;
these
are the
internal
cerebral
veins.
Just behind
the pineal
gland,
these
join with the basal veins
to form
the great
vein of Galen,
and, above
these
veins,
is the splenium
of the corpus
callosum.
The internal
cerebral
veins are readily
identifled as tubular
enhancement
on CT scans
obtamed
after contrast
material
is administered
and as curvilinear
signal
intensity
voids
cxtending
anteriorly
into the cistern
of the yelum interpositum
on plain MR images.
Pineal
and parapineal
masses
elevate
these
PHYSIOLOGY,
AND
EMBRYOLOGY
The pineal
gland
is a small reddish-brown
structure
that is usually
approximately
8 mm
long and 4 mm wide and is attached
to the
upper
aspect
of the posterior
border
of the
third
ventricle
within
the
(Fig
1).
It lies
cerebrospinal
quadrigeminal
in the
fluid
plate
cistern
midline,
(CSF)
and
of the
behind
the
third ventricle.
Anterior
to the pineal
gland
is
the cistern
of the velum
interpositum
(cistern
of the transverse
fissure).
The pineal
gland
develops
from the most
caudal
portion
of the roof of the third ventricle, from an area of ependymal
thickening
that
evaginates
tion
(2).
within
the
ventricle
tion
of the
that
pineal
control
7th
week
is a patent
of gestacavity
connects
is lined
to the
third
by ependyma.
gland
of certain
and
the
there
gland
and
regulation
els
during
Initially,
The
in humans
func-
is twofold:
circulating
of long-term
hormone
(eg,
onset
1evof pu-
berty)
and short-term
(eg, diurnal
or circadian)
biologic
rhythms.
The relationship
between
tumors
of the pineal
region
and the
precocious
onset
of puberty
was documented
at the
end
suggested
ited
of the
that
sexual
past
the
century,
normal
when
pineal
it was
gland
inhib-
pineal
gland
development.
In many
lower
is superficial
and
vertebrates,
the
has
photoreceptor
a direct
function;
in some
species
of lizard,
the formation of a lens overlying
a portion
of the gland
transforms
the pineal
gland
into a dorsal
“third
eye.
Even in humans,
the regulation
of biologic
rhythms
by the pineal
gland
responds
to photoperiodic
cues. The pineal
gland
receives
this light or dark information
“
via
an
accessory
optic
pathway
that
One landmark
for imaging
the pineal
region with computed
tomography
(CT) and
magnetic
resonance
(MR) is the quadrigeminal plate
cistern
(Fig 1). On a routine
axial CT
begins
as
the retinohypothalamic
tract,
passes
through
the spinal
cord by means
of the reticular
activating
system,
and reaches
the gland
through
both sympathetic
and parasympathetic
innervation
(3). The pineal
gland
has two populations
ofcells.
About
95% are a neuronal
type
cell or pinealocyte
with dendritic
processes,
and the other
5% are neuroglial
supporting
cells that resemble
astrocytes.
obtained
veins,
at the
whereas
usual
callosal
inclined
masses
angle,
depress
them.
Just below
rigeminal
the pineal
gland
are the four quadbodies
composed
of the two supenor
and two inferior
colliculi.
These
form the
roof of the dorsal
midbrain,
which
is also
called
the tectum
of the mesencephalon.
The normal
pineal
gland
may not always
be
visualized
within
the quadrigeminal
plate cistern because
of its small size and volume
averaging.
It may appear
isointense
to gray matter
on MR images
and have attenuation
equal
to
that ofgray
matter
on CT scans.
When
the pineal gland
is calcified,
the effects
of volume
averaging
are minimized
on CT scans,
and it is
invariably
visualized.
Normal
pineal
calcifications
are
scans
than
(Fig
observed
more
they
are
on
frequently
plain
on
CT
radiographs
1).
In a large
tients,
review
physiologic
of over
calcification
700
healthy
pa-
at CT
was
set
of puberty,
the
prevalence
of normal
RadioGraphics
#{149}
Smirniotopoulos
Ct
a!
pi-
neal calcification
increases
from only 8% to
1 1% at age 8-14
years
to 40% by age 20 years
(4). Pathologic
studies
suggest
that pineal
caldo
not
change
substantially
with
age, and, although
some
glands
never
most develop
at least some
microscopic
U
not
noted
in patients
younger
than age 5 years
but increased
in prevalence
dramatically
and
almost
logarithmically
with age. After the on-
cifications
578
the
Volume
calcify,
calci-
12
Number
3
fr’
:r
.-..
.,..
‘s
‘,
-..,
‘4p
.
P
-
C-
d.
1.
(a) Normal
pineal
gland. Axial dissection
is a downward
view ofthe
third ventricle
and the thalami;
the
velum
interpositum
has been removed.
The pineal
gland (*) is a pinecone-shaped
mass at the posterior
margin
of
the third ventricle.
Directly
underneath
are the two superior
colliculi
of the midbrain
roof (tectum
or tectal plate,
arrowheads).
The space behind
the midbrain
is the quadrigeminal
plate cistern.
The triangular
space anterior
to
the pineal
gland is the cistern
of the velum
interpositum,
bounded
laterally
by the
curving
medial
borders
of the
pulvinar
(P) ofthe
thalami.
This cistern
extends
anteriorly
over the roofofthe
third ventricle
(removed)
to the foramen
of Monro
and the paired
fomices
(F). The septum
pellucidum
connects
the fornices
with the genu of the
corpus
callosum
(GC). (b) Normal
pineal gland in a 17-year-old
girl (who also has tuberous
sclerosis).
CT scan
shows calcification
in a normal
pineal
gland (*). (The calcifications
in the right frontal
horn are subependymal
nodules of tuberous
sclerosis.)
Note the triangular
space anterior
to the pineal
gland,
bound
by the pulvinar
of the thalami (arrowheads).
The axial plane of the CT section
is actually
at an angle to the true horizontal
plane,
and the
quadrigeminal
plate cistern (Q) appears
U shaped.
Axial Ti- (c) and T2-weighted
(d) MR images
show the quadrigeminal
plate cistern
as a triangle
pointing
backward
(Q) from the pineal gland. The great vein ofGalen
lies
within
the quadrigeminal
plate cistern.
The anterior
extension
of the quadrigeminal
plate cistern
is the cistern
of
the velum
interpositum
(or cistern
ofthe
transverse
fissure).
It is a triangle
pointing
forward
and contains
the tubulax signal intensity
voids of the paired
internal
cerebral
veins (arrowhead).
Figure
May
1992
Smirniotopoulos
Ct
a!
U
RadioGraphics
U
579
fications
at puberty
(5).
However,
the
pres-
AFIP
ence of pineal
calcification
does
not correlate
with any change
in pineal
hormone
activity
and is not a sign of dysfunction
(5).
Although
calcifications
within
the pineal
gland
are usually
normal,
they are also often
seen
in association
plasms.
with
Calcifications
in the
masses
monly
pineal
within
calcium
the
deposits
However,
and
displace
preexisting
the
region
occur
gland
within
the
may
pineal
types
neoplastic
have
normal
Embryonal
Teratoma
as
teratoma,
dysgermi-
carcinoma
Benign,
mature
Benign,
immature
(> 10% immature
Malignant
Malignant
may
calcifications
multipotential
tissues)
calcifi-
tumors
from
Masses
noma)
tissue.
tumoral
(derived
Embryonic
differentiation
Germinoma
(atypical
comthan
cell tumors
Region
cells)
with
most
rather
parenchymal
Germ
of neo-
in association
pineat
teratomas
cations,
various
seen
of Pineal
Classification
immature
teratoma
(histologi-
caily benign
but metastatic)
Extraembryonic
differentiation
to
periphery.
Choriocarcinoma
SYMPTOMS
MASSES
Pineal
signs
twisting
enough
rial
masses
and
headache.
may
symptoms
the
nonspe-
in this
normal
or
may be severe
transtentoarea
may
function
Neoplasms
tissues
‘
‘
(intrinsic)
Less
commonly,
with
pineal
region
hypogonadism
masses
rather
gland)
elements
or adjacent
Ependymoma
pi-
Meningioma
and
three
associated
of supporting
the
Astrocytoma
also
of the
Lymphoma
Nonneoplastic
Pineal
cyst
Lipoma
Arachnoid
Dermoid
Vascular
Metastatic
masses
cyst
or epidermoid
malformations
(inclusion
cysts)
neoplasms
are
than
precocious
puberty.
Diabetes
insipidus
may
occur
if the mass has either
extended
directly
downward
or seeded
the CSF to involve
the
anterior
or inferior
recesses
of the third yentricle
and hypothalamus.
Pineal
region
masses
may produce
a classic
U
PINEAL
REGION
GERM
CELL
TUMORS
which
the patient
is unable
to upwardly
dcviate the eyes and has impaired
ocular
convergence.
This syndrome
results
from the effects
of pressure
on the reflex
nuclei
of the quad-
Masses
of the pineal
region
are commonly
referred
to as pinealomas.
This term was introduced
by Krabbe
as a generic
name
for pineal masses.
This seemed
appropriate
at the
time because,
with routine
light microscopy,
the histologic
features
of many
of these
tumors
appeared
to resemble
pineal
cells. However, later research
in pineal
masses,
coupled
with the advent
of immunohistochernical
rigeminal
stains
neurologic
syndrome,
plate.
defined
In more
advanced
by
Parmnaud,
cases,
in
both
upward
and downward
gaze may be impaired.
When
a patient
presents
with a paralysis of upward
gaze, the possibility
of a pineal
region
mass should
be considered.
Health
nervous
RadioGraphics
U
Smirniotopoulos
Ct a!
and
ultrastructural
studies
(electron
microscopy)
revealed
that most of these
pineal region
tumors
were
not of pineal
parenchymal
origin
(6). Therefore,
pinealoma
is a
misnomer.
The Table
summarizes
the current
terminology
used
at the Armed
Forces
Institute of Pathology
(AFIP) for pineal
tumors.
This
U
( ‘yolk sac’ ) tumor
neoplasms
Astrocytoma
(within
Mixed neoplasms
lead to precocious
puberty.
theories
to explain
precocious
puberty:
(a) interference
with the norma! antigonadotropic
effect
of the gland,
(b) secondary
invasion
into the diencephalon
with destruction
of the sexual
inhibitory
function
of the median
eminence,
and
(c) ectopic
production
of gonadotropins
by the neoplasm.
580
sinus
parenchymal
Pineobtastoma
and
obstruction
aqueduct
downward
Masses
with
neal gland
There
are
Pineal
as seizures
from
of the sylvian
to precipitate
herniation.
produce
such
Hydrocephalus
interfere
Endodermal
PINEAL
Pineocytoma
region
cific
TO
RELATED
U
classification
is modified
from
Organization
classification
system
tumors.
Volume
the
World
of central
12
Number
3
Figure
pecially
splenium
year-old
virtually
internal
2.
(a) Semischematic
of a pineal
mass.
The sagittal
The most
common
lesions
of this region
(over two-thirds)
are neoplastic
derivatives
of
multipotential
embryonic
germ
cells that are
similar,
if not identical,
to gonadal
germ
cell
tumors.
The germ
cell tumors
are classified
by
cell type
and may be benign
or malignant.
Within
the germ
cell tumor
group,
there
is a
separation
between
neoplasms
that form embryonic
tissue
and those
that form extraembryonic
tissues.
Primordial
germ
cells in mammals
develop
from relatively
undivided
embryonic
cells of
the yolk sac wall, near the allantois.
In normal
development,
they move
from the yolk sac,
along
its wall,
and
through
the dorsal
tery of the hindgut.
During
week,
they invaginate
into
(2). This movement
occurs
neously
with the development
cephalon
(eg,
thalamus,
mesen-
the 6th gestational
the genital
ridges
virtually
simultaof the dien-
hypothalamus)
and
pineal
gland
(at 5-8 weeks).
Thus, it is possible that misguided
germ
cells could
become
embedded
in or persist
to surround
the pineal gland.
Aberrant
migration
may also cxplain other
extragonadal
germ
cell tumors
that arise in the retroperitoneum,
sacrococcygeal
area, and mediastinum
(1,6,7).
May 1992
plane
is ideal
those
in the pineal
and sellar
regions.
The internal
cerebral
veins
ofthe
corpus
callosum
from the pineal
gland
below.
(b) Sagittal
boy with a germinoma
demonstrates
a homogeneous
mass in the
equal to that of gray matter.
The germinoma
is just inferior
to the
cerebral
veins
(arrowhead).
for imaging
alt midline
masses,
es-
(heavy
black line) separate
the
Ti-weighted
MR image
ofa 13pineal
region,
with signal
intensity
linear
signal
intensity
void
of the
Germinoma
Germinorna,
formerly
called
atypical
teratoma,
is histologically
identical
to ovarian
dysgerminorna
and testicular
seminoma.
Germinorna
(Figs 2, 3) is the most common
type
of pineal
region
mass,
accounting
for twothirds
of the germ
cell tumors
and 40% or
more
of all pineal
region
neoplasms.
About
80% of intracranial
germinornas
are in the
pincal
area;
the other
20% localize
near the
suprasellar
region,
either
in the third ventricle
or in the cistern.
Male patients
are affected
two to 17 times
more
often
than female
patients.
The peak age of presentation
is in the
2nd decade,
and few patients
are older
than
age 30 years
at initial
observation.
A substantial number
ofyoung
children
( < 10 years of
age) have germinorna
in association
with precocious
puberty.
I
Germinoma
is a malignant
tumor
corn-
posed
of a mixture
oflarge
multipotential
primitive
germ
cells about
15-30
pm in diameter and smaller
cells that resemble
lymphocytes (some
pathologists
believe
they arc reac-
Smirniotopou!os
et a!
U
RadioGraphics
U
581
C.
C.
Figure
3.
Pineal germinoma
in a 2 1-year-old
man. (a) Nonenhanced
CT scan demonstrates
a mass in the region
of
the pineal
gland,
extending
into the dorsal
midbrain
(tectum).
The right side ofthe
mass has higher
attenuation
(arrowhead)
relative
to brain.
(b) Axial Ti-weighted
MR image demonstrates
a hypointense
mass (*) involving
the
tectum.
(c) The mass appears
highly enhanced
after administration
ofgadopentetate
dimeglumine
(Magnevist;
Berlex, Wayne, NJ). (d) Plain sagittal
Ti-weighted
MR image shows slight heterogeneity.
(e) After administration
of gadopentetate
dimeglumine,
the MR image shows homogeneous
enhancement,
with compression
and possible
extension
into the brain stem.
582
U
RadioGraphics
U
Smirniotopoulos
Ct a!
Volume
12
Number
3
ma with seeding.
(a) Sagittal
Tiof a 22-year-old
man demonstrates
tat are homogeneous
and are equal
at of gray matter.
There
is a domical region
and a second
smaller
mass
tern.
(b) Coronal
Ti-weighted
MR
atient
amine
after administration
of gademonstrates
abnormal
enarged pituitary
infundibulum,
which
rom the pineal
germinoma.
(c) Sagit-
brained
at autopsy
of a different
paLtes two prominent
masses.
The origie large
mass in the pineal region.
The
suprasellar
cistern,
represents
CSF
ther, these two masses compress
and
Th
The pineal
mass extends
well be-
nd encroaches
on the roof of the
iso spreads anteriorly,
to the foramen
he cistern
of the velum
interpositum
tive
lymphocytes).
Because
germinomas
Germinomas
are
homogeneous
not encapsulated,
they may invade
the adjacent structures
of the brain
(eg, thalamus)
and easily
spread
along
the surfaces
of the
brain
or through
the flow of CSF (Fig 4). At
initial
presentation,
disseminated
the
patient
commonly
has
disease.
Germinomas
are
plasms
and respond
therapy.
Currently,
very radiosensitive
well to specific
cytotoxic
agents
vinblastine
Adriamycin
sulfate,
neochemosuch as
(doxorubicin
hydrochloride;
Adria Laboratories,
Columbus,
Ohio),
cisplatin,
and cyclophosphamide
are
used for both
intracranial
and testicular
germ
cell tumors
(1). The overall
prognosis
has irnproved
with combined
therapy
and is relatively good,
with a 5-year
survival
of 75% after
radiation
therapy
alone.
May
1992
have
a strong
masses
that
tendency
have
either
to be
attenu-
ation
higher
tamed
Ganti
pineal
equal
to that of gray matter
or slightly
than that of brain
on CT scans
obwithout
the use of contrast
material.
et al (8) reported
that all 15 cases
of
germinomas
studied
without
contrast
material
had attenuation
higher
than that of
brain
(8). They also noted
that in six cases the
neoplasm
was clearly
outside
the pineal
gland
but had surrounded
and engulfed
it. The pineal gland
was seen usually
as a very prominent and calcified
structure
within
the tumor
mass.
Smlrniotopou!os
Ct
a!
U
RadioGraphics
U
583
The
normal
tions
prevalence
detected
at CT
of pineal
This
is true
even
noma
is in the
in the
pineal
ports
(1 1) have
indicated
tions
seen
germinomas
when
suprasellar
area
with
the
cistern
(9,10).
to
a ger-
germi-
rather
Although
that
miliar
40%,
but, for unknown
reasons,
this increases
almost
100% when
the patient
also has
minoma.
This
calcifica-
is approximately
than
most
the
re-
calcifica-
represent
the
engulfed
pineal
gland,
Ganti
et at (8) reported
calcification
within
the substance
of
the tumor
in 10 of their
16 cases.
CSF seeding
of the subarachnoid
space
or the ventricles
was
also
On
noted
in five
MR images,
nomas
tends
of their
the
to be
16 cases
signal
equal
(Fig
intensity
to that
4).
of germi-
of gray
matter
on images
obtained
with both
the short
and
long pulse
sequences;
they are relatively
homogeneous
masses.
Small cystic areas were
noted
in only two of 10 cases reported
by Zee
et at (1 1). The findings
ofa noncalcified,
homogeneous
pineal
region
mass with signal
intensity
equal
to that
of gray matter
seen in a
young
male patient
are strongly
suggestive
of
a germinoma
histologically.
Germinomas
ap-
pear highly
enhanced
and usually
homogeneous
on both CT and MR images
obtained
with contrast
material.
However,
this enhancement
is rather
nonspecific,
since
the
majority
of neoplasms
in this region
do not
have an intact
blood-brain
barrier.
Gadolinium-enhanced
MR imaging
is recommended
to help identify
metastases
from CSF seeding.
.
is more
a male
predilection
Teratomas
cells
are
that
usually
ture
of two
and
tissues
or more
organogenesis,
representing
of the
and
simplistic
a mix-
embryologic
mesoderm,
even
2: 1 to 8:1.
of multipotential
normal
producing
of ectoderm,
sues
neoplasms
recapitulate
layers
endoderm.
organs
Tis-
derived
from
all three
germ
cell layers
are possible.
The spectrum
of differentiation
in a teratoma
can extend
from a multicystic
mass
composed
primarily
of ectodermal
derivatives,
sues
to a complex
mass
representing
to a primitive
(a fetus
or abortive
in fetu).
U
RadioGraphics
additional
and
the
seen
at twinning
most
common
in mature
(including
U
tis-
endoderm,
attempt
However,
type of differentiation
mas is in ectodermal
dermat)
structures.
584
with
mesoderm
Smit-niotopoulos
is often
cyst.”
produces
that
called
Normal
or
terato-
neuroecto-
the
mimics
skin
(erroneously)
skin
epidermoid)
rather
than
erogeneous
teratoma
is the second
most common
region
tumor,
accounting
for approxi1 5% of all masses.
Teratomas
also have
from
teratoma
faand
a “der-
elements
seen
in a
dermoid
include
squamous
epithelium
and
complicated
dermal
appendage
structures
such as hair follicles
and sebaceous
and sweat
glands.
(Epidermoids
only have squamous
epithelium.)
However,
careful
histologic
study
of these
lesions
usually
reveals
small
components
of diverse
tissues,
confirming
their origin
from multipotential
cells rather
than only from ectoderm.
Although
most sacrococcygeal,
retroperitoneal, and gonadal
dermoids
are actually
welldifferentiated
teratomas,
as described
above,
many pineal
and suprasellar
dermoids
are
not. Instead,
most intracranial
dermoids
(and
epidermoids)
are in reality
merely
inclusion
cysts derived
only from ectoderm
rather
than
from multipotential
cells. These
intracranial
“true”
dermoids
arise when
the ectoderm
becomes
abnormally
folded
into the developing head of the embryo.
This occurs
as the
neural
tube closes
and the eye, ear, and face
moid
Teratoma
varies
moid
of development
begin
to form at 3-5 weeks.
These
inclusion
cysts of skin
Pineal
pineat
mately
that
hence
path
mature
are
rnultilocular
multiloculated
likely
to be
(the
typically
true
masses.
Thus,
intracranial
a teratoma
der-
unilocular
than
a hetmass
a more
benign
epithelial
inclusion
cyst. The true inclusion
cyst dermoid
usually
occurs
in the
suprasellar
cistern
and posterior
fossa and is
uncommon
in the pineal
region.
Teratomas
frequently
produce
neuroectodermal
tissues
(with variable
degrees
of differentiation)
that
may
resemble
the
embryologic
neural
tube or a neuroblastoma.
Occasionally,
these
teratomas
with neuroblastic
cells may
mature
spontaneously
into fully differentiated
neural
tissue
(6). Alternatively,
a teratoma
with immature
neural
tissue
may metastasize.
These
metastases
may consist
entirely
of neuroblastic
elements.
Pineal
region
teratomas
can be partially
or totally
encapsulated;
however, they may also be unencapsulated
and
locally
invasive.
In imaging
studies,
teratomas
tend to be
heterogeneous,
multilocular,
ring or ring-enhanced
lesions.
They may have areas
of mixed
CSF, lipid,
and soft-tissue
characteristics,
as
well as calcification
(Figs 5-8)
(10-13).
All
five teratomas
reported
by Ganti
et al (8)
were sharply
circumscribed
masses
with areas
oflow
(fatty)
attenuation
on CT scans,
a feature notably
absent
from all the other
tumor
types in their
series.
They
also noted
turnoral
calcification
in four of their five cases.
et
a!
Volume
12
Number
3
Figure
5.
Teratoma.
(a) CT scan of a 4-year-old
boy demonstrates
gion extending
anteriorly
into the cistern
of the velum interpositum.
a heterogeneous
mass in the pineal reThe mass contains
several large chunks
of calcification
and a darker,
cystic-appearing
area (arrowhead)
. Heterogeneity
like this, especially
when
there
is lipid material
and calcification,
is a hallmark
of a mature
teratoma.
(b) After contrast
material
is administered,
there
is relatively
homogeneous
enhancement
of the noncalcified
solid portions
of the tumor.
The cystic region
does
not appear
enhanced.
(c) Ti-weighted
MR image
of the same patient
demonstrates
a
mildly
heterogeneous
mass largely
isointense
relative
to gray matter.
However,
there
are focal areas of Tiweighted
shortening
(arrowhead)
from lipid material
(eg, sebaceous).
The cystic region
(*) has higher
signal
intensity
than that of CSF because
of proteinaceous
material.
(d) Sagittal
Ti-weighted
MR image
of an 8-yearold boy demonstrates
a grossly
heterogeneous
mass with large amounts
of hyperintense
lipid material.
It extends
anteriorly
toward
the cistern
of the velum
interpositum
and posterior
third ventricle.
Note the cystic
region
(*) . The signal
intensity
void of the internal
cerebral
veins
(arrowhead)
is superior
to the mass,
but, in
addition,
there is a thin rim of hypointensity
encircling
the mass, suggesting
a tumor capsule.
(Courtesy
of L.
Baker,
MD, University
of California,
San Francisco.)
(e) Sagittal
gross specimen
of a mature
pineal
teratoma
from a different
patient
shows
a grossly
heterogeneous
mass that is well encapsulated
(arrowhead).
The varied contents
of this partially
cystic mass include
a superior
portion
with a ‘ ‘cheesy’
‘ consistency
from sebaceous
material.
In the sagittal
plane,
it is clear
that much of this mass is below the tentorium.
(From the L.
Rubinstein
collection,
AFIP.)
May
1992
Smirniotopoulos
Ct
a!
U
RadioGrapbics
U
585
Figures
6, 7.
(6) Teratoma.
(a) Axial CT scan obtained
without
contrast
material
shows
a multicystic
heterogeneous
mass extending
from the pineal
region
anteriorly
into the cistern
of the velum
interpositum.
Note
the multiple
rings of contrast
material
enhancement
that surround
nonenhanced
cystic areas on both the
axial (b) and the coronal
(C) CT scans.
This appearance
is suggestive
of teratoma.
(7) Pineal
teratoma
in a
37-year-old
man. Axial Ti-weighted
MR image
demonstrates
a heterogeneous
mass with two high-signal-in.
tensity
foci ofTi
shortening
from lipid material.
However,
the rest ofthe
mass is homogeneous
and only
slightly
hypointense
compared
with the signal
intensity
of gray matter.
In this case, the radiologic
diagnosis
of teratoma
would
be less confident,
since
hemorrhage
into other
pineal
neoplasms
(eg, choriocarcinoma)
could
have a similar
appearance.
586
U
RadioGraphics
U
Smirniotopoulos
et a!
Volume
12
Number
3
Figure
8.
Ruptured
pineal
region
teratoma
in a 38-year-old
man.
(a) Sagittal
Ti-weighted
MR image
dem-
onstrates
a heterogeneous
lesion
in the pineal
region.
There
are multiple
irregular
high-signal-intensity
foci
from tumor
lipid material.
Note the extension
of the lipid signal
intensity
below
the tentorium
and into the
fourth
ventricle
(arrow)
. (b)
Axial CT scan demonstrates
lipid material
floating
in a layer in the superior
portion of the frontal
horns
of both lateral
ventricles.
There
are multiple
low-attenuation
lipid droplets
in the
sulci of the visual
cortex
and in the quadrigeminal
plate cistern.
(C) Axial
Ti-weighted
MR image
shows
multiple high-signal-intensity
foci, corresponding
to the lipid droplets
seen on the CT scan. Axial Ti- (d) and T2weighted
(e) MR images
demonstrate
a supernatant
lipid layer floating
on the heavier
CSF in the superior
portions
of both lateral
ventricles.
On the T2-weighted
image,
there
are high- and low-signal-intensity
bands
at the lipid interfaces
caused
by a chemical
shift artifact.
On
Ti-weighted
show
evidence
areas
of signal
mas
may
also
limited
solid-tissue
to the
teratomas
surgery,
a chemical
planting
1992
the
cystic
may
rupture
their
meningitis
the
may
components
contrast
as
Terato-
material
CT and MR images.
heterogeneous,
either
areas
spaces
spilling
along
teratomas
lipid
(1 1 , 1 3).
demonstrate
on both
is usually
lining
or
hyperintensity
enhancement
Enhancement
walls
May
MR images,
of fatty
or
(Fig
along
6).
Pineal
spontaneously
varied
(Fig
or at
contents,
8),
or,
the
.
Choriocarcinoma
Choriocarcinomas
all pineal
account
masses
and
lection.
Intracranial
from differentiation
cells
into
They
may
both CSF
dotropin.
for
also
have
associated
placentalike
with
and plasma
human
Their
appearance
than
a male
choriocarcinomas
of the pluripotential
extraembryonic
be
less
elevated
5%
of
predi-
arise
germ
tissues.
levels
of
chorionic
gonaat CT is nonspe-
causing
rarely,
im-
meninges.
Smirniotopoulos
Ct a!
U
RadioGraphics
U
587
C.
ci.
Figure
9.
Yolk sac tumor
in a 9-year-old
boy.
(a) Axial CT scan
obtained
without
the use of contrast
mate-
nat demonstrates
a round,
relatively
homogeneous,
low-attenuation
mass,
engulfing
the calcifications
within
the central
pineal
gland.
Germinomas
are usually
high-attenuation
masses;
thus, other
diagnoses
should
be
considered.
However,
the appearance
is neither
specific
for nor suggestive
ofyolk
sac tumor.
There
is an incidental
dural
osteoma
(arrow)
. (b) Axial CT scan obtained
after contrast
material
is administered
shows homogeneous
enhancement,
which
is also nonspecific.
(c) Axial T2-weighted
MR image
demonstrates
nonspecific homogeneous
hyperintensity
(higher
than the signal
intensity
ofgray
matter)
ofthe
mass.
(d) Sagittal
MR image
obtained
which
is slightly
gadopentetate
cific;
like
sented
plain
germinomas,
by areas
CT
without
scan
the use of contrast
hypointense
dimeglumine
relative
shows
they
of high
and
are
often
attenuation
show
prominent
with
588
U
hyperintensity
short
RadioGrapbics
on
repetition
U
MR
images
time
or
matter.
but
repre-
on
the
contrast
enhancement.
However,
the common
ence of subacute
hemorrhage
in these
vascular
neoplasms
may produce
areas
cal
material
to gray
prominent
preshighly
of fo-
Smirniotopoulos
time
pulse
Ct
a!
minimal
heterogeneity
obtained
after
enhancement.
sequences
This
(1 1, 13).
in the mass,
administration
latter
differentiate
the more
the lipid
atoma.
common
germinoma
but
signal
intensity
suggestive
Endoderma!
of
feature
tentially
.
obtained
echo
demonstrates
(e) Sagittal
MR image
slightly
heterogeneous
can
choriocarcinoma
Sinus
po-
from
may mimic
of a ter-
Tumor
The endodermal
sinus
tumor
(or yolk sac tumor) is another
example
of differentiation
of
the totipotential
germ
cells from cxtraernbryonic tissues
(Fig 9). These
uncommon
tumors
Volume
12
Number
3
a.
b.
Figure
10.
Mixed
germ
cell tumor
(germinoma
and yolk sac tumor)
obtained
without
contrast
material
demonstrates
a heterogeneous
cystic regions
and three
areas of calcification.
The mass is equal
parenchymal
neoplasms
and other
germ cell tumors
could
have
hanced
CT scan shows
homogeneous
enhancement
ofthe
solid
have
histologic
features
of both
yolk
sac endo-
derm
and mesoblasts
(14). They may be associated
with elevated
levels of a-fetoprotein
in
both CSF and serum.
Although
they are more
common
than embryonal
carcinoma,
at least
50%
occur
other
as mixed
germ
specific
cell
tumors
elements
radiologic
combined
(Fig
features
10)
have
with
(14).
been
No
Embryona!
Carcinoma
Embryonal
carcinoma
malignant,
bryonal-type
gested
that
totipotential,
subsequent
of large,
undifferentiated
emIt has been
sugare derived
from a
cells.
all teratomas
wholesale
differentiation
of these
elements
(6) . Embryonal
cell tumors
develop
focal regions
of differentiation
embryonic
(somatic)
or extraembryonic
cental
or vitelline)
tissues.
Therefore,
surprising
that embryonal
carcinoma
quently
found
component
in mixed
may also
from
(jlait is not
is a fregerm
cell
tumors.
When
embryonal
carcinoma
mixed
germ
cell tumor,
it can
be
the
most
gressive
be
the
only
ment
May
1992
component
to produce
and
systemic
hemorrhage,
and
necrosis
are
frequently
assays
may
PINEAL
PARENCHYMAL
NEOPLASMS
Pineal
parenchymal
neoplasms
be helpful
in
U
is composed
epithelial
boy. (a) Axial CT scan
occurring
histologic
features
(14). There
are
no particular
imaging
characteristics
that suggest embryonal
carcinoma
of the pineal
region.
However,
because
these
tumors
are capable
of producing
elevated
levels
of both
a-fetoprotein
and human
chorionic
gonadotropin,
serum
or CSF
differential
diagnosis.
de-
scribed.
.
ses,
in a 17-year-old
mass in the pineal
region.
There
are focal
in attenuation
compared
with brain.
Pineal
a similar
appearance.
(b) Axial contrast-enportions
ofthe
lesion.
may
is part
metastases.
less
than
15%
ofall
pineal
account
region
for
masses.
Un-
like the germinomas,
they have no sexual
predilection
and may be found
in older
patients
who arc beyond
their 2nd decade.
There
are
basically
two types
that arise from the pineal
cells: the pineocytoma
and the pineoblastoma.
In addition,
however,
pineal
parenchymal
tumors
may have ganglionic
and
astrocytic
differentiation,
and various
cornbinations
of these
types
are also possible.
of a
agdc-
Mito-
Smirniotopoulos
Ct
a!
U
RadioGraphics
#{149}589
d.
shows
C.
Figure
11.
Pineocytoma.
(a) Plain
CT scan
a large
and
relatively
homogeneous
mass
in the pineal
region,
with peripheral
displacement
of pineal
calcification
(arrows).
The mass has extended
anteriorly
along
the velum
interpositum.
This is the exploded
pineal
appearance
that suggests
an intrinsic
pineal
parenchymat neoplasm.
(b) Contrast-enhanced
CT scan shows
homogeneous
enhancement
in the mass,
which
assumes
a triangular
shape
as it conforms
to the contours
of the pulvinar
of the thalami
and velum
interpositurn. (C) Axial proton-density-weighted
MR image
shows
the mass is homogeneously
hyperintense;
it is
diamond
shaped
because
it fills the two opposing
triangles
of the velum
interpositum
(anterior)
and quadrigeminal
plate cistern
(posterior).
(d) Sagittal
T2-weighted
image
shows
the mass is under
the internal
cerebral veins
separating
the fourth
The
(arrow)
and extends
anteriorly
the cerebellum
from the brain
ventricle).
pineocytorna
is a tumor
well-differentiated
ally
indistinguishable
normal
590
U
mature
RadioGraphics
pineal
cells
composed
that
histologically
parenchyma
U
(3).
Smirniotopoulos
along
stem,
of
are
virtu-
from
Often
the velurn
interpositum.
and encroaches
on the
the
the
only
Ct a!
The mass also extends
inferiorly,
superior
medullary
velum
(the roof
of
feature
suggesting
a neoplasm
is the presence
of a mass or a clearly
enlarged
pineal
gland.
The pineocytoma
is a circumscribed,
though
unencapsulated
tumor,
that may remain
to-
Volume
12
Number
3
Figure
12.
trast material
Pineocytoma
demonstrates
of brain
yet
dimeglumine
in a 27-year-old
a homogeneous
is slightly
higher
was administered.
than
woman.
mass
that of CSF. (b)
Anteriorly,
there
catty confined
and is unlikely
to spread
by
means
of the CSF. Because
it is a benign
neoplasm,
hemorrhage
and necrosis
arc uncommon.
The pineoblastoma
is a malignant
tumor
composed
of undifferentiated
or immature
pineal
cells. It is a type ofprimitive
neuroectodermal
tumor
similar
to the medulloblastoma,
neuroblastoma,
and retinoblastoma.
Occasionally,
pineoblastomas
produce
ing
both
eyes
and
the
pineal
intermediate
mature
coblastoma,
has
prognosis
diate
neoplasm,
pineocytoma
for
also
this
between
the
blastoma
and
outcome
possible
the
been
latter
dismal
relatively
identified.
lesion
is also
outcome
more
of
immature
pin-
of pincofavorable
pineocytoma.
As the pineal
version
of the primitive
neuroectodermal
tumor,
the pineoblastoma
would
be expected
to have heterogeneous
morphologic features;
whereas,
the benign
pincocytoma,
without
histologic
changes
of necrosis
and hemorrhage,
should
be homogeneous.
May
1992
with
a mixture
and
there
after
gadopentetate
(*).
is considerable
overlap
in
may
A pineoblastoma
is unencapsulated
and
often
invades
directly
into the adjacent
brain
or may spread
by means
of the CSF (either
through
the ventricles
or along
the meninges).
An
However,
is seen
interme-
(trilateral
retinoblastoma).
both
enhancement
cystic region
conthat
The
of retinoretinoblasin the retina
sites,
includ-
gland
Heterogeneous
is a nonenhanced
MR image obtained
without
Signal intensity
is lower than
their appearance
at imaging.
Zee et al (11)
reported
eight cases,
four each of pineocytoma
and pineoblastoma;
two of each type
had calcifications.
When
images
were
obtamed
after gadolinium
contrast
material
infusion
(two pineocytomas
and one pineoblastoma),
both types were
enhanced
homogeneously;
neither
type had cystic areas
(Fig
ii) (11).
In a review
of our own pathologic
material
consisting
of 2 1 pineocytomas
and 1 1 pincoblastomas,
however,
cystic changes
were
identified in one case only, which
was a pineocytorna
(Fig 12); the others
were solid tumors.
Tien et al (13) also described
a heterogeneous
pattern,
but it was seen in two of their
three
cases of pineoblastoma.
Pineocytomas
and pineoblastomas
may
contain
intrinsic
calcifications
within
the neoplasm
in contrast
to the germinoma:
In the
latter
cases,
the tumor
is usually
not calcified
but the pineal
gland
is (8-10,12,15).
In addition, both
types of pineal
parenchymal
tumor
histologic
structures
(rosettes)
reminiscent
blastoma.
Patients
with inherited
toma
may have multifocal
lesions
and may have tumors
in multiple
(a) Sagittal Ti-weighted
(*) in the pineal gland.
peripherally
displace
preexisting
normal
pineal
calcifications.
This produces
an cxploded
pincal
pattern
rather
than the engulfed
pincal
gland
seen with germinomas
(Fig 1 1). This latter
feature
may be valuable
the differential
neoplasms.
Smirniotopoulos
diagnosis
of these
et a!
U
in
uncommon
RadioGrapbics
U
591
Figure
13.
Pineal
cyst in a 32-year-old
woman.
(a) Axial MR image
obtained
after
gadopentetate
dirneglumine
was administered
demonstrates
a cystic mass with a postenor
peripheral
rim of contrast
enhancement,
representing
compressed
normal
pineal
tissue.
The cyst fluid has slightly
higher
signal
intensity
than that of CSF.
(b) Sagittal
image
also demonstrates
a uni-
formly
hypointense
mass, with a small postenor crescent
of gadolinium
enhancement
in
the residual
pineal
parenchyma.
(c) Photomicrograph
(hematoxylin-eosin
stain)
of a specimen from a different
patient
shows
a cystic
space
rimmed
by residual
pineal
tissue.
C.
U
NONNEOPLASTIC
Pinea!
Cyst
Pineal
cysts may
MASSES
.
mechanisms:
lined
pineal
tation,
pathologic
arise
from
persistence
two
of the
different
ependymal-
diverticulum
and
secondary
cavi-
within
an area
ofgtiosis.
In
perhaps
studies,
pineal
cysts
of variable
are reported
to occur
in 25%-40%
lected
patients;
however,
this high
includes
small
cysts
only
a few
size
of unsefrequency
millimeters
in
diameter
(5). Pineal
cysts may be lined
by
ependyma,
rimmed
with gliosis,
or (most
often) merely
surrounded
by compressed
nor-
mal
pincal
may
be
may
resect
cally,
reflect
with
RadioGrapbics
U
Smirniotopoulos
Ct
a!
a bias
only
pineal
Pathologically,
pincal
multiloculated
of the
symptomatic
cysts are
tissue
surrounded
remnants
U
or
and
cysts
are
filled
with a protcinaceous
material.
Although
they
are usually
an incidental
finding
at imaging
or
at autopsy
examination,
when
large,
they may
produce
symptoms.
According
to our own surgical
pathologic
material,
12 of 16 pineal
cysts were
found
in
patients
who presented
with symptoms
directly
related
to mass effect
that was severe
enough
to require
resection.
However,
this
gliotic
592
tissue.
single
with
neurosurgeons
lesions.
most often
Rosenthal
fibers
to
Microscopilined
with
and
arc
by a peripheral
rim of residual
of the normal
pineal
tissue,
often
microscopic
hemorrhage.
Volume
12
Number
3
a.
b.
Figure
14.
Lipoma.
(a) Axial CT scan
shows
a fatty
attenuating
mass
in the pineal
region
that does
hance.
With its homogeneity
and lack of enhancement,
the mass is most likely not a teratoma.
It
most of the quadrigeminal
plate cistern.
(b) Sagittal
Ti-weighted
MR image
shows
a mass in the
nat plate cistern
with homogeneous
high signal
intensity,
similar
to the signal
intensity
from the
ous fat and clival marrow.
As with many other
pineal
region
masses,
it extends
infenorly
(below
rium)
and pushes
the cerebellum
away from the brain
stem.
Pineal
ages,
cysts
are
occurring
tients
(16).
cysts
(without
ripheral
or
rim
to the
cause
the
brain
barrier,
may
outside
(Fig
pineal
tive
into
hancement
the
fluid
neoplasm
a bloodnoted
material
rim
This
may
also
that
ofCSF
show
can
sequences,
content
rim
Intracranial
ence
of lipid
matically
The
fluid
higher
signal
obtained
probably
because
in
in a mass
Most
lesions
fat
that
subarachnoid
space
differentiation
or
develop
as a result
maldevelopment
and
of
does
not
lipomas
the
primitiva
differentiates
arachnoid,
and
the
making
removal
confirming
virtually
im-
a developmental
(19).
intracranial
pineal
lipomas,
region,
are
anomalies
or fewer
cases
mas
are
with
various
in only
(20).
more
often
as those
with
about
In contrast,
anterior
associated
of agenesis
other
developmental
of the
lipocorpus
defects.
Lipomas
typically
on
pres-
mogeneous
weighted
high signal
intensity
on the TiMR image
(Fig 14). Unlike
most
auto-
pineal
or
any
region
contrast
have
other
one-third
(50%-80%)
degrees
and
such
associated
tenuation
differentiated
(adipocytes)
intracranial
lipoma,
possible
congenital
in-
The
mater,
genital
callosum
dermoids.
to either
mesoderm.
be
and
material
refer
congenital
1992
must
teratomas
pia
the
the meninx
normally
the tento-
inner
meningeal
layer of the dura
mater.
Unlike acquired
lipomas
and other
neoplastic
masses,
the developmental
lipomas
usually
do
not grow as expansile
masses.
Instead
of displacing
the adjacent
structures
to the periphcry, normal
vessels
and cranial
nerves
are
often
intimately
incorporated
within
the con-
in the
(16,18).
lipomas
both
into
Posterior
Lipoma
from
structure,
The meninx
cause
en-
images
on
of
bryologic
(19,20).
sugges-
than
cyst.
to
On
residual
center.
ofa
than
protein
Be-
lacks
rather
suggestive
all pulse
tissues
enhancement
cysts
.
May
enhanced
tensity
a high
inter-
(17).
13)
contrast
the
pineal
with
pe-
normally
homogeneous
of a solid
pineal
pineal
tissue
images,
from
tissue
pa-
on MR images.
sequence
produce
im-
20
was
normal
it is therefore
diffuse
pineal
ofsix
enhancement
be gadolinium-enhanced
delayed
MR
confirmation),
the
normal
on
of every
series
pathologic
to represent
displaced
seen
one
In a recent
ring
preted
frequently
in almost
not en-
occupies
quadrigemisubcutane-
CT
homogeneous
scans
and
neoplasms,
low
usually
they
have
may
not
atho-
show
enhancement.
are
within
the
of abnormal
of an
em-
Smirniotopoulos
Ct
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593
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Smirniotopoulos
et
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Volume
12
Number
3
Figure
17.
Vein ofGalen
aneurysm.
(a) and sagittal
(b) MR images show
Axial
a large
rounded
hypointensity
(flow void)
in the pineal
region
(*). The straight
sinus (arrow in b) is also
dilated.
(c) Vertebral
angiogram
shows
shunting
into the vein ofGalen
(*), which
is massively
enlarged.
C.
stem
and
duce
gross
and
thalamic
gliomas
(Fig
enlargement
vertical
extension
infiltration
of the
16)
of those
of the
white
may
graphic
pro-
structures
tumor
matter
tion
through
long
tracts
(eg,
S
Vascular
Vascular
Malformation
malformations
mass
in the
pineal
largement
of the
as a pineal
region
an
adult
the
(Fig
vein
bus
region.
malformation
venous
system;
1992
to the
or
from
or
CT,
distal
sigmoid)
MR,
and
fistuas
arterio-
into
the
obstruction,
of the
transverse,
of
vein;
deep
thrombo-
dural
.
bosis
is present.
an
abnormal
dilata-
as a response
to in-
pressure,
or both.
of the mass on CT
is a nonspecific
a characteristic
finding,
flow
MR
void,
images
unless
re-
throm-
SUMMARY
The
as in
direct
dural
show
usually
flow, increased
enhancement
veal
U
manifest
as well
from
draining
or
en.
may
vein,
a
enlargement
occur
connections
venous
ultrasonography,
Aneurysmal
Aneurysmal
of a parenchymal
produce
in a child,
may
a result
(straight,
also
of Galen
mass
17).
sis, or hypoplasia
May
may
vein
of Galen
arterial
creased
Although
scans
corticospinal).
techniques
of the
most
common
germinoma,
from
pluripotential
pineal
region
a malignant
neoplasm
germ
cells.
mass
is the
derived
Germinomas
are homogeneous
masses
that engulf
a calcifled pineal
gland
and have signal
intensity
equal
to that of gray matter.
The second
most
common
pineal
region
mass is another
germ
cell tumor,
the teratoma.
These
are usually
sinuses
Doppler
various
angio-
Smirniotopoulos
Ct
a!
U
RadioGrapbics
U
595
heterogeneous
and multiloculated
containing
calcification
and lipid
The true neoplasms
of the pincal
include
mature
malignant
pineocytomas
ated
and
pineoblastomas.
inseparable
the
displace
but
two
germ
cell
preexisting
may
be
tumors
pincal
5.
ance of the human
tooldage.J
Pathol
may
be
6.
differenti-
because
from
distinguished
is infiltration
atlas
pro-
stem;
adjacent
they
can
be
relative
to fat.
routine
MR imaging
in depicting
cations
and
of the
accurately
making
localizing
a differential
tamed
be
gion
masses
8.
of
small
calcifi-
importance
use
of contrast
in the
of pineal
be
correct
histologic
suspected
after
characteristics,
have
very
a truly
the
of these
pathognomonic
Acknowledgments:
Williams
for manuscript
Kruger for photography.
We are grateful
preparation
sist Tomogr
1991;
Futrell
NN, Osborn
2.
cranial
germ-cell
tumors:
natural
pathogenesis. J Neurosurg
1985;
LangmanJ.
Medical
embryology.
3.
Baltimore:
Williams
& Wilkins,
178, 318-364.
PreslockJP.
The pineal gland:
tions
1984;
4.
MT,
Gelman
and clinical
5:282-308.
Zimmerman
incidence
R, Hochberg
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RA, Bilaniuk
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J Comput
Assist Tomogr
1991 ; 15:805-810.
Medical
Syndrome,
K, Lin T, Masumura
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neal gland:
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implica-
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Age-related
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Volume
d
10.
12
c
Number
3