PROSTATIC-CARCINOMA WITH SIGNET-RING CELLS - A CLINICOPATHOLOGICAL AND IMMUNOHISTOCHEMICAL ANALYSIS OF 12 CASES, WITH REVIEW OF THE LITERATURE

Prostatic adenocarcinoma with a signet ring cell (SRC) component is a rare, incompletely characterized variant that must be distinguished fr om similar tumors of bladder or gastric origin. In this study, we used mucin and immunoperoxidase stains on formalin-fixed, paraffin-embedde d sections from 12 prostatic adenocarcinomas with SRC components, with antibodies to prostate-specific antigen (PSA), cytokeratins, MIB-1, b cl-2, c-MET, CD44v6, and CD44v7; we performed a comparison study on si x bladder and seven gastric carcinomas with SRCs. The prostatic SRC co mponent was always associated with the usual high-grade adenocarcinoma Both components were positive for PSA, AE1/AE3, and CAM 5.2 (12 cases of 12) and also expressed c-MET (5 cases of 9), CD44v6 (9 of 10), and CDv7 (9 of 10). Only rare cells stained for bcl-2 (3 cases of 9). The mean MIB-1 proliferation index was 8%. Intracellular mucin was identi fied (periodic acid-Schiff with diastase predigestion (PAS-D) in 9 cas es of 10, mucicarmine in 5 of 10, alcian blue in 6 of 10). Bladder and gastric tumors were positive for PSA (3 cases of 6 and 2 of 7, respec tively), using a polyclonal antibody, and for bcl-2 (5 cases of 6, 2 o f 7), c-MET (6 of 6, 6 of 7), CD44v6 (5 of 6, 6 of 7), and CD44v7 (4 o f 6, 4 of 7), with mean MIB-1 proliferation indices of 15 and 35%, res pectively. All were negative for cytokeratin 34 beta E12. We conclude that prostatic adenocarcinomas with SRC components are typically accom panied by high-grade adenocarcinoma; are variably positive for mucin, with PAS-D being the most sensitive stain; show expression of PSA, cyt okeratins, MIB-1, bcl-2, c-MET, and CD44 similar to that shown by high -grade adenocarcinoma components; have a low MIB-1 proliferation index ; and are not always distinguishable from SRC components of bladder an d stomach carcinomas with any of the above stains, including PSA.