Megakaryocytes and ganglion cells mimicking cancer in fine needle aspiration of the prostate.

: In six cases, fine needle aspiration (FNA) directed at prostatic lesions produced specimens containing megakaryocytes or ganglion cells, which are sources of potential diagnostic error in the interpretation of aspirates of the prostate gland. In three cases, apparent accidental penetration of the tip of the transrectal FNA biopsy needle into the ischium instead of the prostate resulted in the aspiration of megakaryocytes and other bone marrow elements; the megakaryocytes mimicked anaplastic cancer. Three additional FNAs of the prostate produced specimens containing a small number of ganglion cells mimicking well-differentiated adenocarcinoma; the accompanying strands of wavy neural tissue served as a clue to the ganglionic origin of these potentially misleading cells. The paucity of "atypical" cells and the sparsity or absence of prostatic epithelium in the aspirates were additional clues to the cytologist that the findings represented an anatomic misplacement of the FNA biopsy needle tip, rather than a prostatic cancer.