Prostatic adenocarcinoma is a rare finding in urine cytology specimens. In order to shed a detectable number of ma-lignant cells into the urine, prostatic adenocarcinoma must infiltrate the prostatic urethra or bladder neck. Therefore, its presence in urine implies an advanced tumor stage and corresponding histologic sections tend to show high-grade architecture (Gleason patterns 4 and 5). A specific diagnosis is nonetheless difficult to render, especially for patients who present de novo with gross hematuria and bladder outlet obstruction suggestive of a primary bladder lesion. An expedited diagnosis of prostate cancer makes important therapeutic options (androgen deprivation or blockade, immunotherapy) available to the patient and minimizes the possibility for misinterpretation as muscle-invasive blad-der cancer, although external beam radiation and cystoprostatectomy might be indicated for locally advanced cancer of either organ.

The key cytomorphologic features of conventional (acinar) prostatic adenocarcinoma are a round nucleus with prom-inent borders and a large central nucleolus. In addition, the cells have a high nuclear-cytoplasmic ratio, granular or vacuolated cytoplasm, and are relatively uniform in size and shape. The cells tend to form clusters with a syncytial appearance and three-dimensional layering, and microacinar groups may be seen. A tumor diathesis is variably pre-sent. Importantly, marked pleomorphism and nuclear hyperchromasia are not features of conventional prostatic adenocarcinoma.