An Unusual Case of Müllerian Duct Cyst in an Adult Male: Radiological Diagnosis and Clinical Implications.

Müllerian duct remnant cysts in males represent an exceedingly rare form of congenital anomaly resulting from incomplete regression of the paramesonephric (Müllerian) ducts during embryological development. We report a rare case of a 30-year-old male presenting with a history of intermittent pain in the right side of the abdomen and lower back for over eight months. There were no urological or gastrointestinal symptoms. A contrast-enhanced computed tomography (CECT) scan of the abdomen and pelvis revealed a well-defined, tubular, peripherally enhancing cystic lesion measuring 3.0 × 3.0 × 7.8 cm, located in the rectovesical space and extending down to the anal verge. The lesion demonstrated fluid attenuation, lacked septations or solid components, and showed no communication with adjacent organs. These features were highly suggestive of a Müllerian duct remnant cyst. The prostate was noted to be small for age, while other pelvic and abdominal organs were unremarkable. Given the unusual presentation and imaging features, this case adds to the limited literature on symptomatic Müllerian duct remnants in adult males. The report emphasises the importance of cross-sectional imaging in accurate diagnosis, differentiation from other midline pelvic cystic lesions, and guiding further management strategies, including the role of MRI and possible surgical intervention in symptomatic cases.