Ductal Adenocarcinoma of the Prostate Presenting With Bladder Invasion and Bone Metastasis: A Case Report.

Ductal adenocarcinoma of the prostate (PDA) is a rare and aggressive variant of prostate cancer with a tendency for advanced local invasion and atypical metastatic spread. We report a case of a 54-year-old male presenting with urinary symptoms and significant weight loss. Imaging revealed a pelvic mass involving the prostate and bladder, with bone metastases to the pelvis and femur. Histopathological examination of transurethral resection specimens demonstrated ductal architecture. Immunohistochemistry showed α-Methylacyl-CoA racemase (AMACR) positivity, patchy cytokeratin 7 (CK7) expression, and negative prostate-specific antigen (PSA) and GATA-binding protein 3 (GATA3). Despite the unusual immunohistochemistry profile, the findings supported a diagnosis of PDA. The patient received radiotherapy and hormonal treatment, resulting in a marked PSA decline (PSA levels declined from 19.94 ng/mL to 0.34 ng/mL over eight months, representing a reduction of approximately 98.3%). This case highlights the diagnostic complexity of PDA, particularly when immunohistochemical findings deviate from classical patterns, and underscores the need for an integrated diagnostic approach in managing aggressive prostate cancer variants.