ABSTRACT
<p><b>OBJECTIVE</b>To study the clinicopathological characteristics of prostatic cystadenoma (PC).</p><p><b>METHODS</b>A sample from surgically removed tissues of a PC patient was examined by conventional pathology and immunohistochemistry. The clinical data and clinicopathological features were analyzed, and the related literature reviewed.</p><p><b>RESULTS</b>The patient was a male aged 55 years, treated by TUVP for dysuria a year before. The tumor was a grey mass, with lots of different sized capsular spaces full of clear white liquid in the cross section. Histologically, the tumor cells were arranged in a sieve-like, microcapsule-shaped or adenoid pattern, lined with cuboidal and columnar epithelial cells, the nuclei located in the base with neither cellular atypia nor mitosis. Concerning the immunophenotype, PSA, PAP and CK7 were positively expressed in the columnar epithelial cells and 34betaE12 in the basal cells, while CK20, P504S, CEA and villin were negatively expressed, with Ki67 + < 2%.</p><p><b>CONCLUSION</b>Prostatic cystadenoma is a rare benign tumor originating in the prostate, with a unique morphological structure, and mostly with the expressions of PSA and PAP.</p>