Abstract
Undifferentiated mammary sarcoma is extremely rare and the diagnosis is made only after exclusion of metaplastic carcinomas and malignant phyllodes tumor. Mammary sarcomas mostly display specified entities like liposarcomas or angiosarcomas. A 18-year-old female presented in 2010 with a right breast lump for which lumpectomy was done and on histopathological examination benign phyllodes tumor was diagnosed. In 2011, there was a recurrence at site of excised margin and on fine needle aspiration (FNA) the diagnosis of benign breast disease was made; a small biopsy was received for which diagnosis of myoepithelial lesion was given. Then, the whole mass was excised, but histopathological examination report could not be followed up. In 2013, she again presented with a mass arising from the previously excised margin; on FNA, it was diagnosed as malignant sarcomatous lesion. Microscopy showed spindle shaped cells in diffuse and fascicular pattern with plump ovoid nuclei; coarse chromatin and eosinophilic cytoplasm were seen. Few round to ovoid cells with eccentric nuclei and showing bi- or multi-nucleation were present. Large area of necrosis and hemorrhage was present, too. No breast glands were found. Later on, diagnosis was confirmed on immunohistochemical examination. The case was considered worth due to the young age of the patient and lack of differentiation of the lesion in any specific type of sarcoma and CD10 positivity.