Hydropic leiomyoma: A radiologic pathologic correlation of a rare uterine tumor

Hydropic leiomyoma is a rare leiomyoma subtype composed of a conspicuous zonal watery edematous stroma that causes compartmentalization of the smooth muscle cells. It exhibits atypical imaging features which can mimic malignancy, so differential diagnosis with malignant uterine tumors such as leiomyosarcoma is crucial for treatment decisions and patient follow-up. We describe the case of a 54-year-old postmenopausal woman presenting with a fast-growing abdominopelvic tumor associated with abdominal bloating, urinary frequency, and metrorrhagia. Radiologic evaluation depicted a voluminous, well-circumscribed, slightly lobulated, heterogeneous mass with mixed solid and cystic components arising from the uterus. Given the postmenopausal patient status, size of the tumor, and uncertainty about a possible malignant origin, an uneventful total abdominal hysterectomy with bilateral adnexectomy was performed as definitive treatment. However, as it is common practice in our institution, a second opinion report of the previous MRI was done before surgery, with the proposed diagnosis being hydropic leiomyoma. Pathologic examination of the surgical specimen revealed a large subserosal tumor with nodules separated by empty spaces and cysts due to watery exudate. Histologically, it was a mesenchymal neoplasm with trabecular and nested architecture, with tumor cells separated by watery fluid without mitosis or necrosis, securing the diagnosis of a hydropic leiomyoma.