Anatomic Pathology / CYTOLOGY OF PROSTATIC ADENOCARCINOMA Prostatic Adenocarcinoma Diagnosed by Urinary Cytology

Prostatic adenocarcinoma rarely may involve the urinary bladder. Prostatic adenocarcinoma and highgrade transitional cell carcinoma (TCC) may coexist and account for the malignant cells seen in urinary cytology. Differentiating prostatic adenocarcinoma cells from those of TCC is important for therapy but remains difficult. A 10-year retrospective search identified 250 patients with high-grade carcinoma in urinary cytology. Among them, 6 cases of tissue-documented prostate adenocarcinoma were identified. The cytologic features of these cases were compared with those of 15 similarly documented cases of high-grade TCC. By using these criteria, 2 additional cases of prostatic adenocarcinoma were diagnosed prospectively. An oval nucleus with smooth borders; fine, powdery, evenly distributed nuclear chromatin and a large prominent nucleolus when present; and lack of significant pleomorphism are most helpful to differentiate prostatic adenocarcinoma from high-grade TCC. Recognizing these cells may be the first clue for the diagnosis of prostate adenocarcinoma. Prostatic adenocarcinoma cells can be detected rarely in urinary cytology specimens. In many of these instances, the patients have a known history of prostate adenocarcinoma, usually of a high grade, which extends to the bladder mucosa and sheds tumor cells in the urine. On the other hand, hematuria due to involvement of the bladder neck or prostatic urethra rarely can be the initial presentation of prostate adenocarcinoma. In this setting, prostatic adenocarcinoma may be first diagnosed by urine cytology. In addition, prostatic adenocarcinoma and transitional cell carcinoma (TCC) can occur simultaneously in a patient. In all of these situations, differentiating prostatic adenocarcinoma from high-grade TCC is important for diagnostic and therapeutic purposes. Although low-grade TCC, well known for a lack of cytologic atypia, may not enter in the differential diagnosis, highgrade TCC can be confused with prostatic adenocarcinoma. Yet, cytologic features that help separate these 2 malignant neoplasms have not been well characterized.1 In the present study, we attempted to develop criteria for this potentially problematic differential diagnostic dilemma by retrospectively comparing the cytologic features of known cases of prostatic adenocarcinoma with those of high-grade TCC in urinary cytology specimens. We subsequently were able to use these cytologic criteria to prospectively diagnose 2 additional patients with prostate adenocarcinoma who initially presented with hematuria with malignant cells in the urinary cytologic specimen. Materials and Methods The computer files were searched for cases diagnosed as “carcinoma not otherwise specified,” high-grade TCC, or prostatic adenocarcinoma from urine and bladder washing specimens between January 1987 and March 1997. Cases of low-grade TCC were excluded since, as mentioned, this type Am J Clin Pathol 2000;113:29–34 29 © American Society of Clinical Pathologists Krishnan et al / CYTOLOGY OF PROSTATIC ADENOCARCINOMA of carcinoma lacks cytologic atypia and usually is not considered in the differential diagnosis of prostatic adenocarcinoma. A total of 6 cases of biopsy-confirmed unequivocal prostatic adenocarcinoma on urinary cytology were available for the study. The cytologic features of these cases were compared with urinary cytology specimens from 15 cases of high-grade TCC. The diagnosis in all of these cases was confirmed by a biopsy. To develop differential diagnostic criteria, the cytologic features of the malignant cells of prostatic adenocarcinoma and high-grade TCC were compared and contrasted with special attention to 12 features: (1) cellularity, (2) shape of cell fragments, (3) size, (4) shape of individual cells, (5) pleomorphism, (6) cell borders, (7) cytoplasmic features, (8) nuclear shape, (9) nuclear border, (10) nuclear chromatin, (11) nucleolus, and (12) background. These criteria were used in a prospective study between April 1997 and April 1999 to determine whether prostatic adenocarcinoma can be recognized in urinary cytology specimens. Prostatic adenocarcinoma was diagnosed prospectively in 2 voided urine specimens and 1 bladder wash specimen from 2 patients.