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Diagnostics Histology, Microscopy and imaging

Case of the Month

Soft tissue tumor

The tumor shown here was resected from the soft tissue of the axilla of a 26-year-old man. The immunohistochemical stains gave the following results: positive for smooth muscle actin (a), and focally positive for microphthalmia transcription factor (b), Melan A; negative for S-100, pancytokeratin and desmin. What is the most likely diagnosis?

Credit: Wei Cui, University of Kansas Hospital



A   Metastatic melanoma

B   Clear cell sarcoma of soft tissue

C   Malignant perivascular epithelioid cell tumor (PEComa)

D   Leiomyosarcoma

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Answer to last month’s Case of the Month…

E. Mammary analog secretory carcinoma (MASC)

This salivary gland tumor is composed of a single cell population of cells arranged into cribriform and microcystic glands, focally containing secretory material in their lumina. Tumor cells have uniform vesicular nuclei with visible nucleoli and a well-developed eosinophilic vacuolated cytoplasm. There are no mitotic figures and there is no necrosis. Overall the tumor appears histologically as a low-grade malignancy resembling secretory carcinoma of the breast (1).


A Skálová et al., Am J Surg Pathol, 34, 599–608 (2010).

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About the Author
William Aryitey

My fascination with science, gaming, and writing led to my studying biology at university, while simultaneously working as an online games journalist. After university, I travelled across Europe, working on a novel and developing a game, before finding my way to Texere. As Associate Editor, I’m evolving my loves of science and writing, while continuing to pursue my passion for gaming and creative writing in a personal capacity.

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