A 70-year-old woman visited a local hospital complaining of a nodulein the right breast, present since 1 month. She was referred to our hospital for further evaluation. Following mammotome (MMT) biopsy, the nodule was diagnosed as myxoid/round cell liposarcoma. She underwent total mastectomy of the right breast. Histological analysis indicated that the tumor was almost entirely composed of proliferating small round mesenchymal cells in amyxoid matrix background with capillary-like vessels with partial necrosis (<10%). Immunohistochemically, p53 positive cells were seen focally (<1%) only, and the Ki-67 labeling index was approximately 20%. Since the surgical margin was histologically positive despite pathologic findings of high-grade malignancy, adjuvant treatment involving local radiation therapy (60Gy) was administered. The patient was free from any symptoms of local recurrence and metastases 1 year and 8 months after surgery.
Keywords: Myxoid liposarcoma; breast; round cell component.