Gastrointestinal Schwannoma: An Unusual Colonic Lesion Mimicking Adenocarcinoma

Abstract

Gastrointestinal schwannoma is a rare, benign pathological entity that can mimic colonic adenocarcinoma and cause diagnostic dilemmas for treatment. A case of a 68-year-old woman with colonic adenocarcinoma who was discovered to have an incidental synchronous bowel lesion that proved to be a gastrointestinal schwannoma and not a synchronous adenocarcinoma is described. Gastrointestinal schwannomas are uncommon in the colorectal region; they are most often located in the stomach. These spindle cell lesions are distinct from gastrointestinal stromal tumours because the tumour cells have a distinct immunophenotype, with strong diffuse positivity for S-100, glial fibrillary acidic protein and vimentin, and corroborative negative staining of CD34, CD117 and smooth muscle markers. Accurate diagnosis and recognition of this benign entity is, therefore, of immense clinicopathological value for accurate planning of therapeutic strategies.

Gastric schwannoma—a rare benign mimic of gastrointestinal stromal tumor

“…What makes each tumor distinct are their histologic features, and more specifically, what immunohistochemical (IHC) markers they stain positively to. It is important to make this distinction, because GISTs have the potential for malignant conversion, while Schwannomas are benign and carry a good prognosis [ 3 ].…”

Rare Case of a Transverse Colon Schwannoma

“…In their 95-patient study examining colonic or rectal schwannoma, a large portion of patients were asymptomatic on diagnosis (36%), but others presented with rectorrhagia, abdominal pain, or constipation [5]. Other studies noted that GI schwannomas can manifest as colonic obstructions or as intussusception [6][7][8].…”

A Rare Case of Colonic Schwannoma

“…Malignant gastrointestinal schwannomas are very uncommon and associated with poor prognosis. 9 Malignancy features of schwannoma on pathological examination are high mitotic index, the size of tumor, high values of Ki-67 index than 10%, and the presence of hemorrhage, necrosis and ulceration on macroscopic examination. 10 The prognosis of benign schwannomas was reported as excellent with complete resection of tumor and additional treatments are not recommended.…”