signet ring cell prostatic adenocarcinoma

Signet ring carcinoma is a rare prostatic carcinoma variant, with about 60 cases reported in the literature.

The true incidence is not known, as the definition of a primary signet ring carcinoma based on the percentage of signet ring cells in the tumour is not established, with the required percentage of the tumour to be signet ring cells ranging from 5% to 50%.

Another difficulty in definition of the signet ring variant is separation from vacuolated adenocarcinoma of the prostate. True signet ring carcinomas should have intracytoplasmic mucin. Most cases are signet ring cell-like adenocarcinoma.

Clinically, men with signet ring carcinoma present at an average age of 68 years (range 50–85 years), often with a serum PSA level above 15 ng/ml, and at an advanced clinical stage. There are no specific gross findings.

Microscopically, signet ring cells are typified by nuclear displacement and indentation by clear cytoplasmic vacuoles. The signet ring cells can grow in sheets, small clusters, and as single cells.

Rarely, signet ring carcinoma cells are detected in mucinous pools. The Gleason grade for signet ring carcinoma should be of a high-grade pattern 5.

Immunostains for PSA, PSAP and pan-CK are positive in most cases of signet ring carcinoma of the prostate. Signet ring carcinoma spreads to lymph nodes and bone, like usual acinar adenocarcinoma.

The outcome for patients with signet ring carcinoma is poor, and response to treatment, including androgen deprivation therapy, is minimal. The mean survival is 28 months.

References

 Histological variants of prostatic carcinoma and their significance. Humphrey PA. Histopathology. 2012 Jan;60(1):59-74. PMID: 22212078