Patient with prostatic adenocarcinoma with plasmacytoid features and an aberrant immunohistochemical phenotype diagnosed by biopsy and a mini-review of plasmacytoid features in the genitourinary system: A case report.

Prostate cancer is one of the most commonly diagnosed malignancies in men. Most of these tumors are adenocarcinomas. Plasmacytoid is a rare variant of adenocarcinoma described by previous studies in the genitourinary system and is characterized by the plasmacytoid appearance of tumor cells with abundant cytoplasm and abnormally placed hyperchromatic nuclei. However, to the best of our knowledge, plasmacytoid adenocarcinoma has rarely been described in the prostate. This report describes a new case of plasmacytoid adenocarcinoma of the prostate diagnosed by biopsy and summarizes the known literature on plasmacytoid features in the genitourinary system. A 62-year-old male patient presented to the hospital with urinary retention, hematuria, weakness and weight loss. The digital rectal examination revealed an irregular enlargement. Laboratory findings showed elevated levels of prostate specific antigen (PSA; 43.6 ng/ml). Transrectal ultrasound showed invasion of the right seminal vesicle. Prostate tumor core biopsies were collected and sent for diagnosis. Histological examination revealed a high-grade prostatic adenocarcinoma Gleason score of 5+5 (total score 10). The tumor cells had a plasmacytoid appearance with abundant cytoplasm and abnormally placed hyperchromatic nuclei. The immunohistochemical phenotype was characterized by abundant positivity for cytokeratin (CK)AE1/AE3 and PSA. By contrast, tumor cells were negative for p63, CK 34BE12 and GATA binding protein 3 (urothelial markers), synaptophysin (neuroendocrine marker). Tumor cells were also negative for E-cadherin, which is particularly indicative of CDH1 alterations. To the best of our knowledge, this is the first description of a plasmacytoid adenocarcinoma of the prostate diagnosed by biopsy, showing an irregular immunophenotype that may indicate somatic CDH1 alterations. The presentation of a novel rare variant of prostatic carcinoma that differs from other neoplasms of the genitourinary system may contribute to an improved understanding of this uncommonly found histological pattern that may also be mandatory due to the clinical and prognostic implications of this diagnosis.