Diffuse schwannoma involving the entire large bowel with huge extramural development: report of a case.

Schwannoma of the large bowel is a rare clinical entity, which has reportedly been recognized to arise from one place with a submucosal tumor morphology. We present herein the unique case of a 25-year-old woman who suffered from a schwannoma diffusely involving the entire large intestine. The patient complained of abdominal distension and imaging studies revealed a giant tumor occupying the whole abdomen, but no confirmed preoperative diagnosis could be made. A laparotomy proved the huge tumor detected preoperatively to be the markedly wall-thickened entire large bowel itself due to the diffuse extramural development of a neoplasm, but no other organs were involved. Biopsy specimens from the tumor were histologically diagnosed as benign schwannoma. However, because of the possibility of malignancy, we later performed a total proctocolectomy followed by an ileal J-pouch-anal canal anastomosis. The final pathological diagnosis was also that of a benign schwannoma originating from the large intestine. The patient remains well without recurrence 15 months after surgery. To the best of our knowledge, no such case of a schwannoma in the entire large bowel has yet been reported in the literature, and the pathogenesis of its occurrence remains unknown.