Metastatic, sarcomatoid, and PSA- and PAP-negative prostatic carcinoma: diagnosis by fine-needle aspiration

Fine-needle aspiration of prostatic carcinoma usually yields an acinar carcinoma that is immunoreactive for prostatic-specific antigen (PSA) and prostatic acid phosphatase (PAP). We report on two FNAs of metastatic sarcomatoid prostatic carcinoma that were PSA- and PAP-negative. Our methods included a review of the medical records and pathology results. Both cases presented with elevated serum PSA levels and prostate needle biopsies with Gleason score 8 and 9 tumors, respectively. Both cases developed retroperitoneal/pelvic lymphadenopathy, and fine-needle aspirations were performed. These showed high-grade, sarcomatoid tumors with marked anisonucleosis. Immunocytochemical staining for PSA and PAP was negative in both cases. Clinical and radiologic evaluation failed to reveal any other potential primary sites. Metastatic, sarcomatoid, PSA- and PAP-negative prostatic carcinoma is a rare diagnosis of exclusion that should be considered in the characteristic clinical setting.