Volume 1, Issue 1


Benign Schwannoma Of The Ascending Colon: A Case Report

December 18, 2009


Schwannomas of the colon are very rare with most cases of gastrointestinal (GI) schwannomas` seen in the gastric and ileal regions1,2. The non-specific clinical presentation, diagnosis in the pre and post-operative stages and what definitive treatment is currently available are the emphasis of the case reported below.

Case report

A 76 year old female with Past medical history of hypertension (HTN) presented to the Emergency room (ER) with complaints of constipation for five days and recurrent abdominal pain which was localized in the lower abdomen, continuous and dull in character. Patient had had recurrent abdominal pain for 2 years during which she had undergone a computerized tomography (CT) guided needle biopsy after colonoscopy and CT abdomen showed a suspicious mass in the right lower quadrant. The results of that CT guided biopsy were positive for hyperplastic changes and melanosis coli and patient`s condition progressively worsened with alternating bowel habits, easy fullness on eating and a ten pound weight loss.

In the ER a computerized tomography of the abdomen was done that showed a large mass measuring 5.1cm x 5cm x 6.8cm in the right ascending colon with involvement of the ileo-cecal valve. Patient was then evaluated by GI service and on colonoscopy found to have a large 7cm rounded mass with superficial ulcerations in the ascending colon (figure 1). Pathological biopsies taken on colonoscopy showed acute inflammatory exudates with inflamed granulation tissue and after consultation with surgery patient underwent an exploratory laparotomy with extended right hemicolectomy.

Figure 1 - CT of abdomen showing schwannoma of ascending colon

CT scan

Pathological results from patient`s segmental resection demonstrated polypoid single cell neoplasm and positive S-100 immuno-histological protein (figure 2) consistent with schwannoma. Post-operatively patient has been pain free with regular bowel movements and healthy appetite. An evaluation by the oncology service recommended no intervention on the basis of the benign nature of the schwannoma and excellent post-operative prognoses3.  Patient has a strong social support system and denies use of cigarettes, alcohol, substance abuse or any history of neoplasm in the family. 

Figure 2 - RT of ascending colon schwannoma on colonoscopy 



Figure 3 - Histopathology of right ascending colon schwannoma 



The incidence of large intestine schwannoma is unknown as our knowledge is limited to few case reports sited in the literature1,3. This case report highlights a similar trend noted in earlier reported cases by Min et al1and Daimaru et al3 about the difficulty in diagnosing benign schwannomas of the colon. Unlike cases presenting in the more common GI schwannoma sites, including gastric and ileal regions2, colonic schwannomas classically present with non specific symptoms such as abdominal pain and constipation4. In a review of 24 cases of GI schwannomas3 in Japan the only colonic case reported was an incidental finding unlike gastro-ileal schwannomas where greater than 70% presented with obstructive like symptoms and melena stool1,4.

The only definitive diagnostic methodology for benign schwannomas of the colon is pathologic sampling after surgical resection; on colonoscopy they appear encapsulated with superficial ulcerations and on tissue biopsy give results inconsistent with schwannoma (as in our case). This is the major reason for a delay in diagnoses typically seen in benign schwannoma of the colon. Our patient was subjected to two colonoscopies and CT scans plus a CT guided biopsy but only arrived at a definitive diagnosis after excision of the colonic mass. In a review of GI Schwannomas by Malatesti et al5 and Fotiadia et al6 segmental resection with wide margins is recognized as the diagnosis and treatment of choice as endoscopy and CT scans lack adequate tissue for S-100 immunohistochemical demonstration which confirms a schwannoma in 50-100% of patients3,7 .

The presence of positive S-100 (together with LEU 7 (HNK-1) immunohistochemical stains also differentiates benign from malignant schwannomas8 and so far less than 10 cases of malignant GI schwannomas have been reported in the literature9,10,11 with poor prognosis and ineffective response to chemotherapy and radiation therapy their aftermath. Our case report emphasizes, for diagnostic and therapeutic purposes, the need for surgical intervention in the management of colonic schwannoma.


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