A case of schwannoma of the sigmoid colon showing high-uptake on fdg-pet

Abstract

Although schwannomas are common in the neck, brain, and extremities, they are relatively rare in the gastrointestinal tract. In particular, schwannomas arising in the large intestine are rare. We present a rare case of schwannoma of the sigmoid colon showing high-uptake on FDG-PET.
A 75-year-old woman developed increased stool frequency and was referred to our department. Colonoscopy showed a submucosal tumor in the sigmoid colon. The tumor showed high-uptake on FDG-PET ; thus, a malignant tumor such as a GIST or a malignant lymphoma was suspected. A laparoscopy-assisted sigmoidectomy was done. On pathology the post-operative diagnosis was schwannoma. There was no sign of malignancy. FDG-PET is one metabolic imaging approach which can also be used to diagnose malignant tumors. However, there are reports that though schwannomas are benign, they may show high up-take on FDG-PET. Thus, high uptake is not always indicative of malignancy.