Pure Foamy Gland Carcinoma of Prostate - A Series of Rare Cases

Abstract

Foamy gland carcinoma (FGC) is a distinct histological variant of prostatic acinar adenocarcinomas. It was first described by Epstein and Nelson in 1996. It is characterized by abundant xanthomatous cytoplasm, pyknotic nuclei, and intermediate Gleason grade. However, FGC with a high Gleason grade exists. FGC is found admixed with conventional acinar adenocarcinoma in 17 to 22% of needle biopsies and 13 to 22% of radical prostatectomy specimens and only rarely found in pure form. We report six cases of pure foamy gland carcinoma of prostate. The mean age in our study was 62.83 years and 5 out of the 6 cases presented with an elevated serum PSA level. Histopathological examination of our cases showed tumor cells with abundant foamy cytoplasm and low nucleo-cytoplasmic ratio. This deceptively benign-looking morphology can mimic nonneoplastic prostatic glands, Cowper’s gland, mucinous metaplasia, and xanthomatous prostatitis and hence often pose diagnostic challenges, especially in core needle biopsies. PNI was detected in two of our cases. PSA and AMACR staining was positive in all our cases (100%). p63 Staining was negative in all four cases where it was performed. Three, two, and one of our cases had a Gleason score of 7, 8, and 6 respectively. The prognosis depends on the Gleason score and the presence or absence of PNI or extraprostatic extension. Three of the cases presented with bony metastasis. We report this case series in view of the rarity and also to raise awareness of this entity which is often missed on small biopsies. Keywords: Foamy gland carcinoma, Gleason score, Prostate