Gastrointestinal schwannomas: a rare but important differential diagnosis of mesenchymal tumors of gastrointestinal tract

Abstract

BackgroundSchwannomas of gastrointestinal tract are rare, mostly benign and notably different neoplasms from conventional schwannomas that arise in soft tissue or the central nervous system. These tumors are of clinical importance since they should always be considered in the differential diagnosis of submucosal lesions of gastrointestinal tract.MethodsSeven patients with a pathologically proven gastrointestinal schwannoma were identified in our series of mesenchymal tumors and reviewed retrospectively. Clinicopathological and immunohistochemical parameters along with the follow-up results were analysed.ResultsThe series included two males and five females, with a mean age 69 years (range, 39–81). Most patients were asymptomatic on presentation, except for two patients with abdominal pain. In the other cases (n = 5), the tumor was an incidental finding during other medical, imaging or surgical procedures. The tumors were located in the stomach (n = 4) and in the small intestine (n = 3) with an average size of 29 mm (range, 12–70). A preoperative diagnosis was achieved only in one case with a CT-guided core biopsy. Otherwise the clinical, intraoperative, endoscopic or radiological findings were unspecific. Patients with gastric tumor underwent either laparoscopic (n = 2) or open (n = 2) gastric wedge resection of the tumor; in the cases of intestinal tumor (n = 3) a segmentectomy was performed. Pathological examination revealed solid homogenous tumors, which were highly cellular and composed of spindle cells with positive staining for S100 protein, and confirmed the diagnosis of schwannoma. All tumors were negative for c-Kit, smooth muscle actin, desmin and DOG-1 and showed very low proliferation index. There were negative resection margins and no malignant variants were recognized. At an average follow-up of 60 months (range, 24–185) all patients were free of disease with no signs of recurrence or metastases and acceptable gastrointestinal function.ConclusionsSchwannomas are rare, slow-growing and mostly asymptomatic gastrointestinal mesenchymal tumors. They are difficult to be diagnosed preoperatively as endoscopic and radiological findings are nonspecific but histological and immunohistochemical features are of paramount importance to differentiate between benign and malignant schwannomas, or other spindle cell sarcomas. The treatment of choice is complete surgical excision without a conclusive preoperative diagnosis, and the long-term outcome is excellent as these lesions are mostly benign.

Rare Case of a Transverse Colon Schwannoma

“…GI schwannomas are more often found within the Auerbach's myenteric plexus and less likely to be found in the Meissner's submucosal plexus [1]. Mostly commonly found in the stomach, GI schwannomas are less frequently found in the rectum, colon, small intestine, or esophagus [4,5]. Within the colorectal tract, schwannomas typically present in the cecum, right colon, and sigmoid with relatively equally found frequency.…”

“…Most GI schwannomas are incidental findings during screening colonoscopy or imaging. During colonoscopy, an incidentally found GI schwannoma appears as a submucosal mass whose overlying mucosa is either smooth in appearance or has an ulceration over the mass [3][4][5]. When found with CT imaging, it appears as an exophytic mass with homogenous enhancement.…”

“…Cystic changes, necrosis, or calcifications within tumors are not commonly found [4]. A preoperative diagnosis is challenging, as endoscopic mucosal biopsy of these lesion provides limited incite that could help differentiate these masses from other mesenchymal tumors of the GI tract such as gastrointestinal stromal tumors (GIST), neuroendocrine tumors, leiomyomas, or leiomyosarcomas [5,9].…”

“…Schwannomas are the tumors originating from schwann cells and their presentation as a gastrointestinal (GI) tumor is very rare, making up a small minority of all GI tumors [1]. Along the GI tract, schwannomas are most commonly found in the stomach and present incidentally during endoscopic examination or computer tomography (CT) scans [2][3][4][5]. Colorectal schwannomas are even rarer and patients are typically asymptomatic, but can present with signs of obstruction and rectal bleeding [5].…”

A Rare Case of Gastric Schwannoma: A Case Report and Literature Review

“…Although GS is a benign neoplasm with an excellent prognosis after complete surgical resection, the clinical or imaging features have not been sufficiently specific to enable a precise preoperative diagnosis, because gastric SMTs are similar in their gross and imaging findings, and the diagnosis by biopsy does not have a high accuracy rate. At present, only a pathological examination can distinguish a schwannoma from other SMTs, with positive staining for S-100 protein, and negative for c-kit, CD34, desmin, or smooth muscle actin [1,4,5].…”