ARID1A deficient undifferentiated spindle cell and rhabdoid sarcoma of the prostate: report of a unique case with emphasis on diagnostic implications.

We report an ARID1A deficient undifferentiated spindle cell and rhabdoid sarcoma of the prostate, adding to the growing spectrum of SWI/SNF driven undifferentiated sarcoma. Rhabdoid cells can be a helpful morphological clue for promoting molecular and immunohistochemical analyses for deficiency of SWI/SNF subunits, in the diagnostic workup of undifferentiated neoplasms featuring epithelioid or rhabdoid morphology.