An Unusual Uterine Extension Revealing a Congenital Diverticulum: Insight Into Müllerian Duct Development.

The genitourinary system undergoes a complex development, making it prone to congenital anomalies. Müllerian duct anomalies are among these, affecting the uterus, cervix, and vagina due to errors in ductal fusion or septal resorption during development. During cadaveric dissection of a 55-year-old female, a 4.6 cm tubular fibrous extension was identified, projecting from the uterine fundus to the posterior aspect of the anterior abdominal wall near the umbilicus. The uterus itself was poorly developed, with an atrophied body, cervix, and conical fundus. A thick fibrous band connected the fundus to the inner abdominal surface. Histological examination (hematoxylin and eosin staining) revealed an atrophied myometrial wall, a poorly developed cystic endometrial cavity with cystic glands and papillary fronds, and fibromuscular tissue covered by serosa. Bilateral adnexal nodules showed fibrocollagenous tissue with cavernous vascular spaces but no ovarian tissue. No cilia, inflammation, endometriosis, dysplasia, or malignancy were identified. Wolffian remnants were excluded based on myometrial and endothelial composition. The findings are consistent with a true uterine diverticulum, a rare Müllerian duct fusion anomaly. Incomplete midline fusion likely created a focal wall defect that dilated under intrauterine pressure. Clinically, such anomalies may predispose to ectopic pregnancy, abnormal uterine bleeding, or dysmenorrhea, and pose surgical risks if unrecognised during cesarean sections or myomectomies.