Artifactual changes mimicking signet ring cell carcinoma in transurethral prostatectomy specimens.

Histologic study of 20 consecutive cases of transurethral prostatectomy (TURP) showed aggregates of signet ring cells in the stroma in all but one case. They were usually associated with dense lymphocytic infiltrates, but occasionally they infiltrated the fibromuscular stroma and mimicked carcinoma. The absence of mucin and of immunoreactivity for prostate-specific acid phosphatase (PSAP) and prostate-specific antigen (PSA) and the focal positive immunoreaction for leukocyte common antigen (LCA) ruled out carcinoma and demonstrated the lymphocytic nature of some of the cells. Ultrastructurally, degenerated lymphocytes as well as vacuolated smooth cells were noted. None of the seven open prostatectomy specimens studied revealed this signet ring cell change. It is concluded that areas of chronic prostatitis in TURP specimens usually show degenerated lymphocytes and stromal cells with signet ring appearance that occasionally can mimic carcinoma. This is an artifact induced by the TURP procedure.