MSCHs occur mostly in the colon and rectum that showed solitary single spindle cell proliferation without axons or ganglion, were not associated with hereditary diseases, revealed a positive reaction to the S-100 protein in immunohistochemical staining. MSCHs of the GI tract are rare benign lesions, which were different from other neural tumors . Recently, a few cases in colon and rectum [5-8], GEJ  , stomach  and gallbladder  have been reported successively. The literatures showed there was a slight female predominance and most often occur in elder people. MSCH usually produces no symptoms and is detected by chance in most of the cases during gastrointestinal endoscopy performed as routine screening, but the patient may present with diarrhea, melena, abdominal pain or abdominal discomfort, and anemia . This case presented abdominal pain, upper abdominal distension and acid reflux, which may be symptoms of atrophic gastritis. Gastrointestinal endoscopy shows that solitary small polyp accompanied or not accompanied by other lesions. In this report, we describe a case of multiple MSCH arising in gastric antrum on the background of atrophic gastritis. The lesions were mucosal uplifts with slight depression rather than polypoid, consisting of poorly circumscribed proliferation of spindle cells in the lamina propria, with benign cytological appearance and by pure Schwann cell immunophenotype. The histologic and the immunohistochemical features of our case were certainly consistent with MSCH.
The histological differential diagnosis of spindle cell proliferation in the stomach includes GISTs, neural tumors, fibrous lesions, and neoplasms of smooth muscle. It is easy to distinguish MSCH from GISTs, fibrous lesions, and neoplasms of smooth muscle with immunohistochemical stains. GISTs are characterized by peculiar immunoreactivity to C-KIT/CD117 and DOG1 antibodies. Fibrous lesions, such as inflammatory fibroid polyps and benign fibroblastic polyps, are benign fibrous lesions negative for S-100. In neural cell tumors, schwannoma, neurofibroma, mucosal neuroma, perineurioma and granular cell tumor are the main differential diagnosis. Schwannoma is the most challenging differential diagnosis, because Schwann cell hamartoma and schwannoma are both proliferation of pure Schwann cells. However, they are different diseases. Schwannoma is a tumor showing expansive proliferation, with S-100- positive cells and/or a lymphoid cuff in the gastrointestinal tract. Unlike schwannomas, Schwann cells proliferate between gastric foveola and lamina propria in MSCH. The lack of axons and ganglion cells argues against lesions such as ganglioneuromas, neurofibromas, or mucosal neuromas. Moreover, these tumors display significant association with inherited syndromes. Neurofibromas have a strong association with NF1 and mucosal neuroma is highly associated with MEN 2B. The case in our report showed no signs of NF1, MEN 2B, Cowden syndrome, or other inherited syndromes. Perineuriomas have perineurial cell differentiation and are positive for glucose transporter-1 and claudin-1 instead of S-100 protein. Granular cell tumor had numerous eosinophilic granules in cytoplasm and oval cell nucleus in contract to spindle cells in MSCH.
MSCH is an uncommon mucosal spindle cell lesion of the GI tract. It is most commonly seen in the colorectum, but can also be found in stomach and gallbladder. MSCH does not associate with inherited syndromes. MSCH is benign lesion and additional treatment, work-up and follow-up are unnecessary.