Low-grade myofibroblastic sarcoma of retroperitoneum: a rare case

Abstract

Low-grade myofibroblastic sarcoma (LGMFS) is an uncommon tumor which develops mainly in the bone or soft tissues of the head and neck region, trunk, or extremities and extremely rarely found in the abdominal cavity. The rarity of the disease and its low-grade features make an accurate diagnosis difficult in most cases. We recently encountered a giant LGMFS which had developed in retroperitoneum and surgically resected with gratifying results. An 18 years old female presented with complaint of left sided abdominal pain since 8 months and left sided abdominal lump since 5 months. Imaging examinations revealed retroperitoneal soft tissue mass, and surgical treatment was scheduled. During operation, a tumor about 20x18x15cm in diameter with its anterior aspect covered with the pancreas, mesocolon and splenic flexure of colon with densely adhered to splenic vessels and left renal vessels was found. The tumor had firm adhesions to the surrounding tissues, and it was excised with concomitant distal pancreato-splenectomy, left nephrectomy and resection of splenic flexure of colon with colo-colic anastomosis. Histopathologically, fusiform cells were arranged in a complicated or storiform pattern, and immunohistochemical staining revealed that the tumor was positive for vimentin and focally positive for α-smooth muscle actin (SMA), negative for desmin, CD34, CD117, EMA, DOG-1 and S-100. Diagnosis of LGMFS was made. During 6 months follow up patient is asymptomatic and ultrasound abdomen is normal. In case of LGMFS, favorable prognosis can be attained by complete resection of the primary lesion and regular follow up of patient by physical examination and imaging modality.