Uterine Müllerianosis.

Introduction: Müllerianosis is a rare pathological entity characterized by ectopic Müllerian-derived tissues, including endometrium, endocervix, and/or endosalpinx. Most reported cases involve the urinary bladder, while uterine involvement is extremely uncommon. We present a case of müllerianosis presenting as a cystic lesion of the anterior uterine wall, and we provide a review of the available literature. Case Presentation: We report a 37-year-old woman with an asymptomatic anterior uterine wall lesion detected 11 years ago on routine ultrasound. Initially measuring 60 × 35 mm, the lesion was surgically excised and histopathologically confirmed as müllerianosis, containing endometrial and tubal-type tissue. Eleven years later, she presented with abnormal uterine bleeding. Ultrasound revealed a heterogeneous lesion with cystic areas and uterine asymmetry suggestive of adenomyosis. Conservative management, including curettage, failed, necessitating total abdominal hysterectomy. Histopathology confirmed adenomyosis and endometriosis in addition to prior findings. Discussion: This case is notable for the long follow-up, the uncommon anterior uterine location, and the large lesion size. It supports an embryologic or metaplastic origin of müllerianosis and suggests potential links with other uterine pathologies. Surgical excision remains the treatment of choice, while imaging, histopathology, and immunohistochemistry are essential for accurate diagnosis. Long-term monitoring is recommended due to recurrence risk and the rare potential for malignant transformation. Conclusions: Our report emphasizes the importance of awareness, careful diagnosis, and extended follow-up in managing rare uterine Müllerian lesions.