Ascending Colon Schwannoma Surgically Treated after Accurate Preoperative Diagnosis

Abstract

Colorectal schwannomas are rare and usually benign gastrointestinal mesenchymal tumors. However, these tumors are often overtreated, possibly owing to misleading malignant potential. To our knowledge, there have been no previous reports of ascending colon schwannoma preoperatively diagnosed as benign schwannoma. Herein, we report a case of ascending colon schwannoma accurately diagnosed by endoscopic biopsy and successfully treated by wedge resection. The patient was a 76-year-old woman with complaints of bloody stool. She had no relevant past medical history. Radiological findings revealed a protruded mass in the ascending colon, and colonoscopy revealed a submucosal tumor measuring approximately 3 cm in diameter with a reddish and uneven surface. Histological and immunohistochemical analysis for vimentin and S100 protein of the specimen obtained by endoscopic biopsy confirmed the diagnosis of schwannoma. Thus, we performed laparoscopy-assisted endoscopic full-thickness resection of the ascending colon wall, as appropriate for a benign soft tissue tumor. The postoperative course has been uneventful for 2 years. This case demonstrates that colonic schwannoma can be successfully treated with adequate resection if an accurate preoperative diagnosis is made, thereby avoiding overtreatment, such as surgery for colorectal tumor including lymph node dissection. Preoperatively diagnosed schwannomas should be treated by wedge resection, with postoperative pathological findings confirming the presence or absence of malignancy. Additional resection should be considered for very rare cases of coexisting malignant tissue.

Schwannoma of the colon: a rare submucosal neoplasm

“…Unlike their classic pathological features, colonic schwannomas lack pathognomonic clinical signs and symptoms,6 and most of them are found either incidentally on imaging or as a submucosal mass on colonoscopy. In the majority of cases (74%), the diagnosis of schwannoma is made postoperatively only after histopathological and immunohistochemical examination of the resected specimen 1 3 4. In the remaining 26% of cases, the diagnosis is made endoscopically, first identified as a wide-based sessile submucosal lesion, which is then confirmed on biopsy 3 5.…”

“…They are usually slow growing, benign tumours 2. Of the GI schwannomas, colonic ones are the rarest, with only 96 previously reported cases in the literature to date 3…”

Schwannoma of the rectosigmoid colon

“…[ 9 13 14 15 ] Additional resection should be considered for very unusual cases with coincident malignant tissue. [ 16 ] The use of radiotherapy and adjuvant chemotherapy have not been advised because of benign behavior presentations. [ 17 18 ] There is a rare incidence of lymph node involvement with loco-regional and liver metastases in aggressive tumors (2%) depending on the large size (more than 5 cm) with multiple mitoses in mitotic index calculation.…”

Sigmoid colon Schwannoma simulating colon cancer

“…Normally they are asymptomatic, therefore, the diagnosis is often accidental after an endoscopy. They are usually found in smooth muscle, and by CT, they are homogeneous exophytic tumors that could present cystic changes, necrosis and calcifications (1,(3)(4)(5). The diagnostic challenge is that this is a submucosa lesion, therefore, the endoscopy biopsy is only performed in the mucosa.…”