Prostatic adenocarcinoma with atrophic features: a study of 202 consecutive completely embedded radical prostatectomy specimens.

Prostatic adenocarcinoma may manifest with morphologic features that may be mistaken for benign glandular atrophy. The incidence, morphometric extent, and diagnostic attributes of atrophic prostatic adenocarcinoma have not been defined in radical prostatectomy cases. The size, grade, and stage at which prostatic carcinomas manifest atrophic change and whether these atrophic appearing adenocarcinomatous glands are proliferative, quiescent, or dying (apoptotic) also have not been established. To characterize prostatic adenocarcinoma with atrophic features, we studied 202 consecutive completely embedded radical prostatectomy specimens from previously untreated patients. The histomorphologic attributes of atrophic carcinoma were compiled and compared with benign atrophy and usual prostatic adenocarcinoma without atrophic features. The atrophic carcinoma volume was quantitated by image analysis, the proliferation index was determined by Ki-67 immunolabeling, and the apoptosis index was assessed by TdT [terminal deoxynucleotidyl transferase]-mediated dUTP [deoxyuridine triphosphate]-biotin nick end labeling (TUNEL). Of 202 prostatic adenocarcinoma cases, 32 (15.8%) demonstrated atrophic features. The malignant glands resembled benign atrophic glands by showing profound cytoplasmic volume loss, yet these glands almost always (96.4%) exhibited an infiltrative growth pattern, always lacked basal cells (confirmed by 34betaE12 immunostaining), and exhibited nuclear atypia with nucleomegaly and nucleolomegaly. The atrophic carcinoma foci had a mean volume of 0.3 cc (range, 0.01-2 cc), representing a mean of 16% of total carcinoma volume. The mean proliferation index for atrophic prostatic carcinoma was 4% compared with 1.2% for benign atrophy and 5.3% for usual nonatrophic carcinoma. Apoptosis was identified in only 1 of 32 atrophic prostatic carcinomas. Carcinomas with and without atrophic features did not differ in histologic grade, tumor volume, or pathologic stage. Most atrophic carcinomas were moderately differentiated, of Gleason grade 3. We conclude that the atrophic pattern of prostatic carcinoma is a distinctive morphologic presentation of proliferating, intermediate-grade, prostatic adenocarcinoma that has significant diagnostic rather than prognostic implications.