http://www.oncopathology.info.

Atrophy

• looks suspicious for adenocarcinoma at first glance.
• the nuclei are small and hyperchromatic.
• No prominent nucleoli are seen.
• Some glands are lined by obviously benign flattened atrophic epithelium.
• The immunostain for high molecular weight cytokeratin can be helpful in distinguishing between atrophy (fragmented basal cell layer) from atrophic variant of prostatic adenocarcinoma (no basal cell layer).

Atypical adenomatous hyperplasia

• It may show the infiltrative architecture of cancer,
• lacks the cytologic features such as prominent nucleoli.
• The immunostain for high mol. wt. Cytokeratin will show fragmented basal cell layer in most cases.

Post-Atrophic Hyperplasia

• Post-atrophic hyperplasia architecturally mimics adenocarcinoma
• lacks the cytologic features.
• In difficult cases, the immunostain for high mol. wt. cytokeratin can be performed which would show at least a few basal cells in post-atrophic hyperplasia.

Sclerosing Adenosis

• small glands with infiltrative growth pattern in a cellular spindled stroma.
• The plump spindle cells in the stroma are nicely seen here.
• The lining acinar epithelial cells lack cytologic atypia – no significant nuclear or nucleolar enlargement is seen
• Myoepithelial differentiation in basal cells of the acini of Sclerosing adenosis is illustrated with the immunostain for muscle specific actin.

Cowper’s Glands

• They have a lobular configuration and are often associated with skeletal muscle fibers
• The glands are lined by goblet cells distended with mucin.
• The small hyperchromatic nuclei are pushed to the periphery.
• Sometimes ducts lined by cuboidal cells are present in the center of the lobules.

Mucinous Metaplasia

• Mucinous metaplasia is seen in about 1% of prostates.
• It may occasionally resemble prostatic adenocarcinoma. However, it lacks prominent nucleoli and the does not show immunoreactivity for PSA and PAP.
• The cells are positive for PAS, mucicarmine and Alcian blue.

Prostatic xanthoma

• Prostatic xanthoma is an uncommon benign lesion that may mimic high-grade prostatic adenocarcinoma.
• It consists of lipid-laden macrophages that may be arranged in small circumscribed nodules or infiltrating cords extending into the stroma
• diffusely positive for CD68 (shown here), and negative for CAM5.2, PSA, and PSAP.

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