Adenoid Cystic (Basal Cell) Carcinoma of the Prostate: A Rare Entity with Diagnostic Challenges and Therapeutic Uncertainty

Background Adenoid cystic carcinoma (ACC), also referred to as basal cell carcinoma (BCC) of the prostate— a term used synonymously in the literature to describe the same clinicopathological entity— is an exceedingly rare malignant neoplasm. Initially described in the salivary glands by Billroth in 1859, ACC is characterized by cribriform, glandular, and basaloid architectural patterns. Prostatic involvement is exceptional, with only isolated case reports and small case series documented in the literature. We report a rare case highlighting the clinicopathological and immunohistochemical features essential for accurate diagnosis. Case Report A 69-year-old man presented with hematuria. Digital rectal examination and ultrasonography revealed an enlarged, hard, nodular prostate, while serum prostate-specific antigen (PSA) levels were within normal limits. Transurethral resection of the prostate (TURP) chips revealed a malignant neoplasm composed of basaloid and cribriform patterns. Immunohistochemistry demonstrated diffuse tumor cell positivity for high-molecular-weight cytokeratin (HMWCK) and BCL2, with negativity for PSA, AMACR, GATA3, CK7, synaptophysin, CD56, and chromogranin. A high Ki-67 labeling index (60–65%) supported the diagnosis of adenoid cystic (basal cell) carcinoma. Conclusion Prostatic ACC/BCC is a rare malignancy that can clinically and histologically mimic other prostatic tumors. Normal PSA levels, in conjunction with a characteristic immunophenotype, are critical for accurate diagnosis. Early recognition is essential given the tumor’s variable biological behavior and potential for aggressive progression.