MALIGNANT CYSTIC EPITHELIAL-STROMAL TUMOR OF THE PROSTATE

A huge cystic tumor in the pelvis of a 62-year old man, cytologically by fine needle aspiration biopsy, was composed of malignant spindle ce lls and transitional as well as glandular epithelial cells. Histochemi cal, immunostaining, and ultrastructural studies of the aspirated spec imens and on the radically resected tumor indicated that the neoplasti c cells are of prostatic fibroleiomyomatous stromal and epithelial ori gin. The lesion did not extend to the urothelium of the urinary bladde r. This tumor resembles the rare cystadenoleiomyofibroma of the prosta te, yet the cytologic abnormalities suggest a malignant potential Long -term follow-up and recognition of additional cases are necessary to d efine the biologic behavior of this neoplasm.