Urachal Carcinoma with Divergent Glandular Enteric-Type and Squamous Differentiation Associated with Bladder Exstrophy: Case Report of an Extremely Rare Entity.

Background and Clinical Significance: Urachal carcinoma (UrC) is an uncommon neoplasm derived from residual embryonic structures connecting the bladder to the umbilicus. Owing to its rarity, deep anatomic location, and histologic overlap with other glandular malignancies, accurate diagnosis remains challenging. Congenital anomalies of the lower urinary tract, including bladder exstrophy, are recognized as conditions that may predispose to malignant transformation of urachal remnants, although documented cases remain scarce. Case presentation: We describe the case of a 52-year-old male with bladder exstrophy and intellectual disability who presented with a progressively enlarging suprapubic mass and intermittent hematuria. Radiologic evaluation demonstrated a mass arising along the urachal tract. Surgical excision revealed a tumor composed of two morphologically distinct components: an enteric-type adenocarcinoma and a squamous carcinoma. Immunohistochemical profiling indicated urachal derivation and excluded other primary sites. Conclusions: This case expands the morphologic spectrum of UrC and emphasizes the diagnostic value of integrating clinical risk factors with detailed histologic and immunophenotypic assessment, particularly in tumors with mixed differentiation patterns.