Introduction and objectivesVarieties of prostatic adenocarcinoma whose architectural and cytological appearance mimicked benign lesions have been reported in recent decades. Such neoplasms include xanthomatous (foamy) carcinoma and pseudohyperplastic carcinoma. We recently studied five carcinomas showing a cytoarchitectural combination of both neoplasms which were mistaken for benign glandular proliferations. MethodsFive cases (1.8%) of pseudohyperplastic carcinoma showing xanthomatous changes were selected from a total of 280 biopsies showing prostate carcinoma. Glandular prostatic hyperplasia was originally diagnosed in four such cases. ResultsPatient age ranged from 54 to 78 years (mean: 64 years). All patients had high prostate-specific antigen levels, and digital rectal examination showed abnormalities in four. Neoplasms showed minimal atypia and consisted of mid- to large-sized glands arranged in nests resembling hyperplastic nodules. Glands showed papillary projections, infoldings, and undulations. Most nuclei were basal, small and hyperchromatic, and nucleomegaly was observed only occasionally. Several useful criteria for the diagnosis of acinar carcinoma, such as perineural infiltration, mitosis, crystalloids, blue secretions, and prostatic intraepithelial neoplasia, were absent. ConclusionsProstatic carcinoma with a pseudohyperplastic pattern and xanthomatous changes mimics hyperplastic glands. Timely detection is critical to avoid treatment delay.