Mucin poor mucinous tubular and spindle cell carcinoma of the kidney, with nonclassic morphologic variant of spindle cell predominance and psammomatous calcification.

ABSTRACT

Mucinous tubular and spindle cell carcinoma (MTSCC) is a rare type of kidney tumor that has only been recently described. The classic MTSCCs are polymorphic renal neoplasms characterized by small, elongated tubules lined by cuboidal cells and/or cords of spindled cells separated by pale mucinous stroma. Nonclassic morphologic variants and features of MTSC have not been well studied and rarely been reported. We report a challenging case of mucin-poor MTSCC with marked spindle cell predominance and focal psammomatous calcification in a 39-year-old man and describe its histologic and immunohistochemical features. Pathologists must be aware of the histologic spectrum of MTSCCs to ensure their accurate diagnosis.