A case of retroperitoneal desmoid-type fibromatosis that involved the unilateral ureter after gynaecologic surgery

INTRODUCTION: Desmoid-type fibromatosis represents a rare, benign, soft tissue tumour that is locally invasive with high recurrence potential. PRESENTATION OF CASE: We encountered a case of retroperitoneal desmoid-type fibromatosis in a 45-year-old woman who presented with chief complaints of stomach ache and vomiting. She underwent total abdominal hysterectomy and left salpingo-oophorectomy due to uterine myoma and a paroophoritic cyst at 42 years of age. Abdominal computed tomography showed a 5-cm left retroperitoneal tumour and severe hydronephrosis of the left kidney. Multiple imaging studies failed to provide a definitive diagnosis. Therefore, we performed tumour resection, right salpingo-oophorectomy, ureterectomy, and ureterocystostomy. The tumour surrounded the left ureter and adhered to the left internal/external iliac artery, rectum, bladder, and the edge of the vagina. Histopathologic examination yielded a diagnosis of retroperitoneal desmoid-type fibromatosis. One month after the operation, transvaginal sonography showed a 2-cm mass in the pelvis. We suspected tumour recurrence and commenced pharmacotherapy with tranilast (300 mg/day, three times per day). Four months after the operation, the mass disappeared. DISCUSSION: There are minimal reports of postoperative intra-abdominal desmoid-type fibromatosis and preoperative diagnosis is difficult. To the best of our knowledge, there are no reported cases of desmoid-type fibromatosis that involved the ureter with severe hydronephrosis following a gynaecologic operation. CONCLUSION: We experienced a case of retroperitoneal desmoid-type fibromatosis that involved a unilateral ureter after gynaecologic surgery.