| Abstract|| |
Sarcoma of the breast constitutes less than 1% of all malignant breast tumors and liposarcoma of the breast has an incidence of 0.3% of all the mammary sarcomas. A 47-year-old woman presented with a mass in the right breast and mammography was suggestive of a malignant lesion. Modified radical mastectomy was performed. The tumor was diagnosed histologically as a pleomorphic liposarcoma. The patient was discharged and her postoperative recovery was uneventful.
Keywords: Breast neoplasms, liposarcoma, pleomorphic
|How to cite this article:|
Mardi K, Gupta N. Primary pleomorphic liposarcoma of breast: A rare case report. Indian J Pathol Microbiol 2011;54:124-6
| Introduction|| |
Liposarcoma is one of the rarest malignant breast tumors and comprise 0.003% of all breast tumors.  Very few cases of pleomorphic liposarcoma (PLS) have been reported in the literature.
| Case Report|| |
A 47-year-old female presented with a lump in the right breast since 1 year. She noticed a rapid increase in the size of lump in the last 1 month. On physical examination, there was a 5×4 cm sized, well defined, mobile lump in the upper outer quadrant of right breast, which was not adherent to overlying skin or underlying muscles. Multiple lymph nodes were enlarged in the right axilla. Mammography showed a high-density mass with marginal irregularity. Ultrasonography also revealed a 5×4.3 cm solid mass. The patient underwent modified radical mastectomy.
On gross examination, serial sectioning of the mastectomy specimen revealed a well-circumscribed growth measuring 4.5×4×3.5 cm. Cutsurface of the tumor was variegated with solid gray-white areas, yellowish areas, friable necrotic areas, as well as cystic areas [Figure 1]. Fourteen lymph nodes were found in the axillary tail. On microscopic examination, areas with lipogenic characteristics were surrounded by nonlipogenic areas. In lipogenic areas, pleomorphic lipoblasts of different size and shape were found [Figure 2]. The number of lipoblasts also varied considerably from field to field. In nonlipogenic areas, sheets of pleomorphic spindle cells with scattered multivacuolated lipoblasts were seen [Figure 3]. Significant necrosis was present. A panel of antibodies was studied immunohistochemically: vimentin, S-100, desmin, CD34, CD68, cytokeratin, epithelial membrane antigen (EMA), myoglobin, myogenin, and smooth muscle actin (SMA). Positivity for CD68 and myogenin were observed rarely. Staining for cytokeratin was negative. CD 34 and SMA were positive only in vessel walls, and negative in tumor, while other antibodies yielded no specific staining. The case was diagnosed as primary PLS of the right breast.
|Figure 1: Cross-section of mastectomy specimen showing a circumscribed tumor with necrotic areas|
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|Figure 3: Photomicrograph showing pleomorphic spindle cells with scattered lipoblasts (H and E, ×40)|
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| Discussion|| |
Sarcoma of the breast constitutes less than 1% of all malignant breast tumors. Primary liposarcoma of the breast is an extremely rare lesion and has an incidence of 0.3% of all the mammary sarcomas.  PLS is the rarest subtype of liposarcoma and is discriminated from other high-grade sarcomas by the presence of pleomorphic lipoblasts.  In breast, this malignancy may arise directly from mammary interlobular stromal tissue, or it can develop as a component of a cystosarcoma phyllodes. ,
Primary liposarcoma of the breast occurs in patients ranging from 19 to 76 years of age, with a median age at occurrence of 47 years.  These tumors manifest as slowly growing, painful breast masses of variable duration. This is in contrast to the rapid growth seen in the setting of malignant phyllodes tumor.  Breast liposarcoma is generally unilateral at presentation. Axillary lymph node metastasis and skin changes are very rare.
The typical gross appearance of these tumors shows a median size of 8 cm in greatest diameter; however, they may grow much larger, reaching up to 20 cm in diameter.  These masses are generally well circumscribed or encapsulated. Up to one-third of the tumors show an irregular, infiltrated, or lobular pattern of growth. Depending on histology, the cut surface may be gelatinous, reflecting a myxoid component, or firm and yellow to tan in color. Larger tumors may show areas of necrosis.
Differential diagnoses include lesions or tumors containing vacuolated cells that may be confused with lipoblasts. , Silicon granuloma, fat necrosis, myxoid malignant fibrous histiocytoma, and signet ring cell carcinoma may contain vacuolated cells. The recognition of typical lipoblasts that have scalloped, irregular, hyperchromatic nuclei with sharply defined intracytoplasmic vacuoles is the key feature in differentiating liposarcoma from others. It is well recognized that lipoblasts are "in the eye of the beholder," and although the phenomenon has not formally studied, there is clearly some degree of interobserver variation in the identification of lipoblasts.  This is particularly true when a high-grade spindled or epithelioid neoplasm infiltrates fat, which may result in the isolation of single or small groups of adipocytes that resemble lipoblasts. The distinction from nonlipogenic tumors is based on the demonstration of multivacuolated lipoblasts and occasional positivity for S-100 protein in the spindle or poorly differentiated areas. In distinction from poorly differentiated epithelial neoplasms, the positivity of occasional cells for epithelial markers should be kept in mind.  In breast, malignant phyllodes tumor with focal liposarcomatous differentiation should be ruled out by extensive sampling of the tumor to exclude the characteristic glandular component.
The recurrent chromosome translocation t(12;16)(ql3;pll) has been widely reported as a specific marker for myxoid liposarcoma. Myxoid and round-cell liposarcomas share a key genetic defect, the fusion of truncated TLS and CHOP genes. Molecular studies in PLS so far yielded little useful results: in one-third of the patients MDM2 amplification was detected, and TP53 alterations were present in four out of nine patients (all without MDM2 amplification). 
Unlike most sarcomas of the breast, PLS occasionally metastasizes to axillary lymph nodes. Metastasis primarily occurs via the blood stream. When there is no evidence of metastatic spread, classical radical mastectomy is the treatment of choice. When there is evidence of metastatic disease, radiotherapy will have a palliative effect.
In conclusion, PLS is a rare tumor of adulthood that occurs most commonly in the deep soft tissues of the extremities and are extremely rare in the breast. It behaves as a high-grade sarcoma that frequently metastasizes, most commonly to the lungs. Histologically, most examples of PLS are MFH-like, differing by the presence of pleomorphic lipoblasts. This tumor has a wide range of histologic appearances, but no clinical or pathologic feature appears to be predictive of a more aggressive clinical course.
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