A Case of Parasitic Leiomyoma in the Sigmoid Mesentery Following Total Laparoscopic Hysterectomy.

Parasitic leiomyoma (PL) develops when fragments of a morcellated uterine leiomyoma, during procedures such as laparoscopic myomectomy (LM) or total laparoscopic hysterectomy (TLH), adhere to other tissues. We recently encountered a case where PL developed in the mesentery of the sigmoid colon following TLH. A 51-year-old woman had previously undergone TLH with in-abdominal morcellation. Six years post surgery, she presented with a new mass in her lower abdomen. MRI showed a large tumor (21×12×15 cm) in the pelvic cavity, initially suspected to be a leiomyoma or potentially a malignant tumor, such as a sarcoma or gastrointestinal stromal tumor (GIST), due to its size and unusual location. During the tumor resection, the tumor was found adhering to the sigmoid colon mesentery. Histopathological examination confirmed it was a benign leiomyoma, and the patient's recovery was uneventful. For large PL, differential diagnosis can be challenging. Demonstrating a solid tumor of unknown cause after gynecologic surgery, especially after myomectomy or myoma morcellation, a parasitic myoma must be included in the differential diagnosis. It is crucial to conduct thorough preoperative evaluations and ensure informed consent by discussing the potential for malignancy and the corresponding treatment options.