Primary rhabdomyosarcoma of the prostate. Diagnosis by needle biopsy and immunocytochemistry.

Needle aspiration biopsy of the prostate in a patient who initially presented with multiple metastatic lesions in the lungs and a pleural effusion showed the presence of many malignant cells. These cells appeared either as noncohesive round and oval cells or as clusters. The cytologic impression that these were sarcoma cells was confirmed by subsequent histologic and immunochemical studies. By correlating the cytologic, histologic and immunochemical findings with the clinical findings, it was possible to determine that the primary site of the tumor in this patient was the prostate. Our experience in this case suggests that air-dried smears stained with Romanowsky stains are suitable and useful for cytodiagnosis.