A 77 year old man with a 5-year history of prostate nodular hyperplasia presented with urinary obstructive symptoms. Transurethral resection consisted of 22 grams of prostatic chips. The majority of the chips revealed nodular hyperplasia. About 30% of the specimen showed areas of white fleshy tissue with cribriform proliferation measuring 2.3 cm in aggregate.

Tumor nests of various sizes infiltrate myxoid stroma with poorly circumscribed border (Fig.8.1). There are 2 distinct architectural patterns: The first pattern is predominant consisting of nests and trabeculae of cells arranged in a cribriform pattern with microcystic spaces containing basement membrane material (Fig.8.2 A, 8.2B, 8.2C ). The second pattern: nests of basaloid cell with scant cytoplasm and peripheral palisading ( Fig.8.3A, 8.3B). This tumor is strongly positive for high molecular weight cytokeratin 34bE12 ( Fig.8.4).

The differential diagnosis includes atypical adenomatous hyperplasia (Fig. 8.5), sclerosing adenosis ( Fig. 8. 6A, 8.6B), basal cell hyperplasia ( Fig. 8.7), atypical basal cell hyperplasia ( Fig. 8.8A, 8.8B), basal cell adenoma , post-atrophic hyperplasia ( Fig 8.9A, 8.9B), high-grade prostatic intraepithelial neoplaisa (PIN) cribriform pattern (Fig 8.10), and prostatic adenocarcinoma cribriform subtype ( Fig. 8.11)/

Adenoid Cystic/Basal Cell Carcioma (ACBCC) of the Prostate

Key Features:

• Poorly circumscribed nests or trabeculae of cells infiltrating myxoid stroma
• There are two distinct architectural patterns: adenoid cystic and basaloid
• Adenoid cystic pattern: Nests of cells arranging in a cribriform pattern. Microcystic spaces contain mucinous material
• Basaloid pattern: Variably sized round basaloid cell nests with prominent peripheral palisading
• The tumor cells are positive for high-molecular weight cytokeratin and/or p63
• The tumor cells are positive for cytokeratin 7 and negative for cytokeratin 20
• Extraprostatic extension, perineural invasion, and macronucleoli may be present
• Potentially aggressive neoplasm requiring ablative therapy

Follow-up: The patient died of tumor with lung metastasis 3.5 years after the diagnosis.

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