Benign Schwannoma of the Sigmoid Mesocolon: A Pediatric Case Report

Abstract

Schwannomas are benign neurogenic tumors derived from Schwann cells, which line the peripheral nerve sheath. These tumors rarely occur in the mesentery. In this report, we describe a rare case of benign schwannoma of the sigmoid mesocolon in an 11-year-old male. He initially presented with abdominal pain and had an abdominal mass in the left upper abdomen. Laboratory tests including measurement of tumor marker concentrations showed no abnormal findings. On the basis of ultrasonography, computed tomography, and magnetic resonance imaging findings, he was preoperatively diagnosed as having malignant lymphoma in the mesentery. Laparotomy showed that the tumor was covered with a thin capsule and was located in the sigmoid mesocolon. The tumor was completely excised without colon resection. Histologically, the tumor exhibited Antoni A- and B-type components. Immunohistochemistry showed that the tumor cells were diffusely positive for the S-100 protein but negative for α-smooth muscle actin, c-kit, and CD34. These findings were compatible with benign mesenteric schwannoma without malignant transformation. The patient’s postoperative course was satisfactory, and no evidence of recurrence was found 5 years after the surgery. Because mesenteric schwannoma is rare in children with abdominal tumors, preoperative diagnosis may be difficult.