Mammographic changes following conservation therapy for breast

Transcription

Mammographic changes following conservation therapy for breast
Mammographic changes following conservation therapy for
breast cancer
Poster No.:
C-0395
Congress:
ECR 2010
Type:
Educational Exhibit
Topic:
Breast
Authors:
H. Khan, D. Lister, E. Denton, H. Daintith, M. Alattar, S. Tenant, L.
Grosvenor; Leicester/UK
Keywords:
breast cancer, postoperative, recurrence
DOI:
10.1594/ecr2010/C-0395
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Learning objectives
1. To familiarize ourselves with the normal postoperative mammographic appearance
after breast conservation treatment.
2. To be able to distinguish normal post operative changes from cancer recurrence.
Background
Post operative mammograms of women who have undergone breast conservation
can be a challenge since postoperative changes such as scarring and distortion can
mimic or mask tumour recurrence. Many normal findings can also mimic or mask
tumour recurrence. Skin thickening, architectural distortion, scarring and other indicators
of malignancy can be seen in both malignant and benign conditions like benign
breast surgery, trauma, and breast conservation treatment (BCT) for cancer. Thus,
understanding the expected postsurgical imaging findings is important in ensuring an
accurate interpretation and monitoring recurrence especially as breast conservation
treatment is increasingly being employed.
Tumour recurrence occurs at a rate of 1 % per year, and occurs at the lumpectomy
site earlier than other sites in the breast . [1] It is recommended that all these
patients are followed up by regular clinical examination and mammography. Intervals
vary according to local practice. However, the optimum interval remains unclear with
guidelines suggesting mammography should be carried out every 1 to 2 years for up
to 10 years and, more recently, annually for five years. This article primarily discusses
post surgical mammographic findings because mammography is the primary imaging
modality. Breast ultrasonography, CT scans and MRI are increasingly being employed
as adjuvant to mammography in difficult cases. This paper illustrates and reviews the
common mammographic features of treated breast.
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Images for this section:
Fig. 1: The graph depicts the frequency of occurance and stabilization of characteristic
normal mammographic findings and appearance of changes of recurrent disease.
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Imaging findings OR Procedure details
The four most common breast interventional procedures are percutaneous biopsy;
excisional breast biopsy; BCT; and breast reduction, augmentation, or reconstruction.
The pathophysiology of postsurgical changes, as observed on mammograms, on the type
of surgical intervention and the time elapsed since the procedure. These stabilize with
time while recurrent disease manifests after 18 months.[
on page 72]Postsurgical
mammographic findings can be classified into two general categories: acute changes
and chronic changes.
Acute mammographic changes refer to the immediate postoperative period extending
for the first several weeks and months and include hematoma, seroma, and oedema.
Chronic changes refer to findings identified after the acute period, usually several
months to years after surgery. These include scar formation, retraction, development
of dystrophic calcifications, fat necrosis, and architectural distortion. Nearly all these
changes are transient excluding calcifications. Additional treatment with radiation and /
or chemotherapy will alter healing as well as exaggerate these changes.
This paper reviews and illustrates some of the comon mammographic features of treated
breasts.
SKIN THICKENING:
Skin thickening is the most common finding post conservation treatment.
Normal skin thickening is 0.5 -2 mm, but it may reach up to 10 mm post radiotherapy[3]
It follows the same time course as generalized breast oedema being maximum at 6
months post radiotherapy. It is most marked in patients given Iridium implants and
chemotherapy [4]. Changes are most prominent in dependent portion of breast and
areolar region. Skin changes resolve during a period of 2-3 years although significant
number (20-40%) of patients will have residual thickening for years.[3,4,5]
MASSES:
Hematoma, seromas, breast abscesses and fat necrosis can manifest as well defined
water density masses on page 11. Seromas will exhibit fat-fluid level on lateral view.
However, this would rarely be required these days as ultrasound is readily available. This
is an insignificant finding and nearly all seromas/hematomas resolve in 2-6 months and
eventually replaced by scar, although few may still be detectable after one year.[3,6]
Abscesses on the other hand present as redness of breast and a tense and tender mass
associated with constitutional symptoms like fever and chills.
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LYMPHOEDEMA:
The increased density of breast can be attributed to skin and trabecular thickening, and
oedema of breast tissue. These changes subside with time being maximal at 3-6 months
after completion of radiation therapy. Resolution may be slow and take 2-3 years or in
some cases persist for years[3,4]
In patients with dense breasts, coarsening of stroma is best appreciated in subcutaneous
fat where cooper ligaments are seen. Oedema that increases after stabilization should
be considered as suspicious and warrants further investigation. Fig 2. on page 7
PARENCHYMAL DISTORTION:
Architectural distortion can be due to parenchymal scaring, fat necrosis or recurrent
cancer. Although both cancer and scar can present as spiculated masses, any spiculate
mass in the early post operative period (6-12 months) is likely to be a scar. Tumour
recurrence is unlikely before 18-24 months. Scar is better seen in one view than on the
other. It is seen as a spiculate, poorly defined lesion with a radiolucent centre rather than
a dense central mass. The radiolucent areas are due to entrapped faton page 13.
The spicules are thick and curvilinear. [7]Additionally, scar will shrink and retract as it
matures and stabilizes.
Clinically, a scar will manifest as induration rather than a distinct mass.
CALCIFICATIONS:
Calcifications may develop at lumpectomy site in 30% to 50% of patients and mostly
due to fat necrosis [5]. Other causes include dystrophic calcifications, necrotic tissue and
suture calcification and new or recurrent cancer.
Calcifications are the most important markers of new or recurrent cancer. In a series
by Stromper et al, 43% of mammographically detected recurrences were manifest by
microcalcifications[8].Calcification does not follow a predictable course and may appear
anytime after completion of radiation. The interval to appearance does not predict
malignant potential. Irregular linear or branching and granular microcalcifications are
more indicative of recurrence. on page 22 Benign calcifications are characterized
as punctate, coarse needle like, thick calcified plaques, thin arcs of calcium around
radiolucent oil cysts[9]. Calcifications of fat necrosis are typically coarse and round with
radiolucent centres on page 11while plaque like angular calcifications are associated
with parenchymal and subcutaneous scars. Thick linear branching forms, double tracks
and calcified knots represent calcified suture material. A spot compression magnification
view will best define the morphology and is recommended. In a recent paper by Gunhan
et al, all recurrences in their study showed pleomorphic (100%) morphology with either
clustered (66%), linear (17%), or regional (17%) distribution. No cases of calcifications
with benign (M 2) or probably benign (M 3) morphology represented recurrent disease.[8]
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Clinical Signs of Recurrence in Treated Breast:
Increase in breast size, increase in firmness in previous area of thickening or new
palpable mass should prompt further diagnostic assessment. All clinical findings
suggestive of recurrence can be caused by benign processes like fibrosis, fat necrosis,
infection or inflammation in quarter of patients. [2] In some patients recurrence is
manifested as inflammatory cancer with erythema and increased oedema with or without
associated mass.
Detection and Diagnosis of Recurrent Cancer:
Clinical examination and mammography are both extremely important for detection of
recurrence and complimentary in follow-up and management of patients.
Overall, mammography will identify or confirm local recurrence in two thirds of women.
[10]
Radiographic changes post treatment excluding calcifications are maximal at 6-9 months
and regress thereafter. Progression beyond this timeframe should be considered
worrisome. New or increased ASD at the scar site, increased thickening or generalized
increased density should be considered suspicious and warrant further investigations. on
page 17 Calcification is important indicator of recurrence in 40-50 % of cases. [11] The
positive biopsy rate is much higher for indeterminate or suspicious calcifications at the
site of previous cancer surgery. It is important to note that newly occurring calcifications in
the treated breast are usually benign, and can be managed conservatively in many cases
by using morphology and distribution pattern as a guide. Although benign calcifications
usually develop sooner than malignant calcifications, the time of onset cannot reliably be
used as a guide because of the overlapping times of development of both. Accuracy of
interpretation is furthered by familiarity with the clinical background and careful review of
sequential studies and magnification views.
Page 6 of 25
Images for this section:
Fig. 1: The graph depicts the frequency of occurance and stabilization of characteristic
normal mammographic findings and appearance of changes of recurrent disease.
Page 7 of 25
Fig. 2: differential diagnosis of breast lymphedema
Page 8 of 25
Fig. 3: First MLO view shows faint microcalcifications from HGDCIS. Later view is a
routine followup 18 months later showing an elongated water density mass in the surgical
excision site in keeping with benign seroma.
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Fig. 4: CC and MLO views of another patient showing a well defined mass with mild
associated parenchymal distortion in keeping with a large residual seroma.
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Fig. 5: RT MLO and CC views after WLE show a typical oil cyst at the site of surgery.There
is surrounding parenchymal distortion and skin deformity.These will represent normal
postoperative changes.
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Fig. 6: Patient had WLE 2 years back. Recent surveillance mammogram show a irrgular
mixed density mass at the surgical site containing central lucencies and faint linear and
punctate calcifications.Appearance is typical of fat necrosis.
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Fig. 7: 18 months first surveillance mammogram showing parenchymal distortion at the
site of WLE.Also note the skin retraction and mild lymphedema. All these are normal post
operative changes.
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Fig. 8: RT MLO and CC view of 65 year old patient who had WLE, Radio and
chemotherapy in 2006.Patient c/o tenderness over scar.Mammograms show a scar with
central luceny due to fat necrosis.Ultrasound pictures below ill defined shadowing mass
with central fluid collection.yellowish fluid obtained on aspiration.
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Fig. 9: Another patient with WLE LT MLO and CC views showing classical changes of
fat necrosis seen as spiculated mass with central lucency.
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Fig. 10: 50 years old patient had WLE of left breast 6 years back. Recent surveillance
mammograms show spiculated mass (circled) at the site of previous scar when compared
with mammograms 18 months back.(LT MLO and CC view recent and 18 months back
put back to back.)
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Fig. 11: Series of MLO views from first surveillnace mammogram from 1998 to
latest screening in 2009.Extensive lymphedema and skin thickening seen on theinital
radiograph has substantially resolves. However the latest mamograms show a new dense
15 mm spiculated mass confirmed as recurrent cancer on biopsy.
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Fig. 12: Cranio caudal views of same patient as above showing a new masss.
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Fig. 13: Patient operated for 18 mm IDC in 1997.First MLO view show preoperative
mammogram. Second two images taken in 2000 and 2007 show scarring at the site of
surgery with development of dystrophic calcifications.
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Fig. 14: Sequential MLO views after WLE of left breast cancer.First Xray on the left is the
initial examination showing lymphedema. Second Xray shows resolution of edema and
appearance of faint benign calcifications.The last Xray on the right demonstrates a new
15 mm spiculated mass at the site of WLE and progression of benign calcifications.
Page 20 of 25
Fig. 15: CC views of the same patient above showing a new mass after stabilization and
increasing benign calcifications.This was confirmed as IDC.
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Fig. 16: Classical dense branching and plaque like calcifications around a radiolucent
centre would be compatible with calcified scar.
Page 22 of 25
Fig. 17: Spot magnification view of new linear and branching microcalcifications in patient
treated conservatively for DCIS.Stereotactic biopsy was performed:Histlogy:Recurrent
DCIS.
Page 23 of 25
Conclusion
Familiarization with the spectrum of mammographic findings in treated breasts is
essential in differentiating postoperative complications from recurrence. Although the two
entities overlap each other, post operative changes have characteristic sequence from
evolution to stability. Changes in mammographic appearance after stabilization ( 12 to
18 months) should raise suspicion of tumour recurrence.
Personal Information
Dr Humaira Khan
Consultant Radiologist
University Hospitals of Leicester
UK.
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