CASE OF THE WEEK
2019-11 / APRIL 29
(CONTRIBUTOR: HUIHUI YE)
A 57 year-old male underwent radical prostatectomy for Grade group 2 prostatic adenocarcinoma diagnosed on biopsy. Upon microscopic examination, a glandular lesion was identified in the left anterior prostate, in addition to a large tumor nodule of Grade group 2 cancer in the right posterior. The following images are representative of the left anterior lesion which showed strong and diffuse staining with PAX2 (shown) and racemase, and negativity for PSA and WT-1.
Quiz
What is the most likely diagnosis?
a. Prostatic adenocarcinoma with atrophic features
b. Nephrogenic adenoma/metaplasia
c. Mesonephric remnant hyperplasia
d. Simple atrophy of the prostate
1. c
Mesonephric remnant hyperplasia
Considering the immunophenotype and the morphology, the diagnosis is florid mesonephric remnant hyperplasia. Mesonephric remnant hyperplasia is a rare benign mimicker of prostatic adenocarcinoma. Common locations include anterior fibromuscular stroma (as in this case) and posterior toward the base. Typically, it is composed of bland cuboidal cells growing in small to medium sized acini or glands, or cystically dilated tubules. Colloid materials can be present in the lumens. In this case, it is predominantly small acinar proliferation with an infiltrative pattern, resembling prostatic adenocarcinoma. Nephrogenic adenoma/metaplasia is another rare benign mimicker of prostatic adenocarcinoma and may share some overlapping features with mesonephric remnant hyperplasia. Features that favor nephrogenic adenoma/metaplasia include variable growth patterns, hobnail cells, thickened basement membrane, stromal inflammation, and peri-urethral distribution.
Mesonephric remnant hyperplasia involving prostate and periprostatic tissue: findings at radical prostatectomy. Chen YB, Fine SW, Epstein JI.
Am J Surg Pathol. 2011 Jul;35(7):1054-61
Huihui Ye
UCLA Health, Los Angeles
HYe@mednet.ucla.edu
Prostate
mesonephric, hyperplasia, atrophy, prostate