A rare case report: Bladder endometriosis at the urachus.

Endometriosis is an uncommon condition, and its occurrence in the urachus is exceptionally rare. This case report highlights the extreme rarity of bladder endometriosis involving the urachal area. To the best of our knowledge, no such cases have been previously reported in the literature. The clinical presentation and imaging findings of this condition are extremely similar to those of urachal carcinoma, which makes the differential diagnosis particularly challenging. In this case, a 34-year-old woman presented with significant bladder irritative symptoms during menstruation. Imaging revealed a mass in the urachal region, but its characteristics remained uncertain. Cystoscopy showed only bladder compression, and the patient ultimately underwent robot-assisted laparoscopic partial cystectomy. Postoperative pathology confirmed the diagnosis of bladder endometriosis. This case underscores the importance of considering bladder endometriosis in the differential diagnosis of masses in the urachal area, particularly when they resemble urachal cancer. Early surgical intervention and histopathological confirmation are essential to prevent disease progression.