Is mammary not otherwise specified-type sarcoma with CD10 expression a distinct entity? A rare case report with immunohistochemical and ultrastructural study

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/9019879588725702 webciteMammary sarcomas are very rare and most display specified entities just like liposarcomas or angiosarcomas. There are still a few cases in the absence of specific differentiation, which were diagnosed of pleomorphic sarcoma or malignant fibrous histiocytoma and so on [1]. Leibl and Moinfar reported seven cases of not otherwise specified-type sarcoma with the most significant feature of consistent CD10 expression, which were designated as NOS-Type sarcoma with CD10 expression (NSCD10) and were considered as a variant of sarcomas with myoepithelial differentiation [2]. We also experienced one case of such sarcoma with diffuse and strong expression of CD10. Herein, we present the data of histology, immunophenotype and ultrastructure of the case and discuss in detail.A 45-year-old female presented with a giant mass in the left breast. The lump was first noticed by the patient herself six years ago. The tumour was only about 1cm in diameter at that time and grew slowly, thus no treatments were adopted. The tumour grew rapidly in the past half a year and its diameter reached 10 cm or so, therefore, the modified mastectomy and axillary lymphadenectomy were performed in our hospital.The tumour appeared a circumscribed neoplasm without envelopes, measuring 12 cm？×？12 cm？×？8 cm. The cut surface was solid gray in fish appearance with haemorrhage and necrosis in the central area (Figure 1). Under microscopic inspection, the tumour was found to be mainly composed of spindle cells interspersed with varying collagen bundles. The spindle cells were arranged in fascicles, occasionally in storiform pattern (Figure 2A). The collagen in most areas was scarce and inconspicuous (Figure 2B), whereas in some focal regions was rather ample (Figure 2C). Cytological observation showed that the cells displayed eosinophilic or amphophilic cytoplasm with ill-defined boun