A Review Leveraging a Rare and Unusual Case of Basal Cell Carcinoma of the Prostate

Abstract

Basal cell carcinoma (BCC) is a rare nonacinar variant of prostatic carcinoma. In spite of prostatic acinar adenocarcinoma being one of the most common carcinomas in prostate, <100 prostatic BCC cases have been reported to date. Adenoid cystic/cribriform histology has been described in varying proportions to occur in prostatic BCC and is reported to be associated with aggressive behavior and high risk of metastasis. Herein, we present a case of prostatic BCC with adenoid cystic morphology, comprehensively describe its immunohistochemical and MYB/MYBL1 gene rearrangement findings, discuss its differential diagnosis, and review the literature of this rare entity.

Figure 1

Representative hematoxylin and eosin images (a–f) revealing tumor composed of variably sized irregular solid nests of basaloid cells and anastomosing tubules with desmoplastic stroma (a, 100x magnification). Focal peripheral palisading with peritumoral clefting (b, 100x magnification), comedonecrosis (c, 200x magnification), and invasion into the bladder neck (d, 100x magnification) was noted. Cribriform architecture with eosinophilic hyaline material in the lumen resembling adenoid cystic carcinoma (e, 200x magnification) and perineural invasion (f, 200x magnification) were also present.

Figure 2

Immunohistochemistry and cytogenetics studies support the diagnosis of prostatic BCC. The tumor cells revealed strong and diffuse reactivity for Bcl-2 (a, 200x magnification), variable multilayer reactivity for basal markers such as p63 and HMWCK (b, 200x magnification). Ki-67 staining showed high proliferation of >30% (c, 200x magnification). The tumor was negative for NKX3.1 (d, 200x magnification) and racemase (b, 200x magnification). Break-apart FISH for MYB image did not show separation of 5′MYB and 3′MYB (E).