Foamy Gland Variant of Prostatic Adenocarcinoma (FGVPA), diagnostic pitfalls: A case report and literature review

Abstract

A transurethral resection of prostate (TURP) specimen was received from a 72-year-old male who presented with a recent history of urinary tract infection and increased serum prostate specific antigen (PSA) of 15 ng/mL. There was an atypical glandular proliferation of which a predominant population demonstrated abundant pale xanthomatous cytoplasm with small hyperchromatic nuclei and inconspicuous nucleoli. A minor component of conventional prostatic acinar adenocarcinoma was identified focally in the background. Immunohistochemistry was used to confirm the diagnosis of adenocarcinoma. FGVPA is a rare variant, with foamy cytoplasm due to intracytoplasmic vesicles not lipid or neutral mucin, and usually with small pyknotic nuclei with minimal atypia. Gleason scoring is performed by the underlying architectural pattern. Immunohistochemistry of basal cell markers and AMACR are often used to confirm a diagnosis of prostatic adenocarcinoma; however, it is to be noted that variants of prostate cancer including FGVPA are labelled with AMACR in only 60–70% of cases. It is important for the pathologist to be aware of FGVPA as in its pure form can easily be missed especially on needle core biopsy. The differential diagnoses of benign mimics with clear cytoplasm include xanthoma, Cowper’s glands, clear cell cribriform hyperplasia and mucinous metaplasia.