A case of prostatic adenocarcinoma with aberrant p63 expression: Presentation with detailed immunohistochemical study and FISH analysis

Prostate carcinomas showing aberrant diffuse-nuclear p63 expression are extremely rare, and there is only 1 article in the literature reporting a series of 21 such cases. We document an additional case of p63-positive prostatic adenocarcinoma in a 60-year-old man, whose diagnosis was difficult. The patient was found to have an elevated prostate-specific antigen (PSA) level at a general health check-up and was referred to the hospital. His serum PSA was 4.2 ng/mL. Digital rectal examination and transrectal ultrasonography did not reveal a lesion. Transrectal needle biopsy of the prostate detected atypical, small prostatic glands suspected for adenocarcinoma at 2 cores. However immunohistochemistry showed nuclear p63 expression in the suspicious glands. Repeat biopsy revealed only high-grade prostatic intraepithelial neoplasia. In the third transrectal biopsy, finding of the same atypical glands showing perineural invasion facilitated the diagnosis of malignancy. The patient underwent a radical prostatectomy. Five different small tumor foci were seen in the prostate after pathological evaluation, one of which was p63 positive and the others p63 negative. The largest of the classic p63-negative tumors showed a TMPRSS2-ERG translocation by fluorescent in situ hybridization while the p63-positive tumor did not. The authors submit that this subtype (p63-positive prostate adenocarcinoma) should be listed among the recognized rare variants of prostatic adenocarcinoma.