Differential diagnosis of submucosal gastric tumors: gastric schwannomas misdiagnosed as GISTs

Schwannomas commonly occur in the head and neck region but are rarely seen in the gastrointestinal tract; the stomach and small intestine are the most commonly involved sites. These tumors are usually misdiagnosed as gastrointestinal stromal tumors (GISTs) before histopathological confirmation due to radiological similarity. GI schwannomas show positivity for S100 protein and vimentin but are negative for CD 117 and CD 34, which helps in differentiating the tumor from GISTs. Case 1: a 70-year-old woman was referred to our hospital by complaints of abdominal pain and discomfort. Upper GI endoscopy demonstrated a protruding lesion at the lesser curvature of the gastric body, and fine-needle aspiration biopsy showed chronic inflammation without malignancy. Since the lesion was suspected to be GIST, this patient had surgery, and a gastric schwannoma was resected successfully. Case 2: a 66-year-old female with anemia and abdominal discomfort was found to have a submucosal elevated mass at the greater curvature of the antrum. Fine needle aspiration biopsy was suggestive of a spindle cell tumor resembling GIST. The patient underwent subtotal gastrectomy with Roux-en-Y reconstruction. Histopathology confirmed schwannoma. It is necessary to differentiate gastric schwannomas from other submucosal tumors of the stomach, especially GISTs. Surgical complete resection of schwannomas usually has a good prognosis with a low probability of recurrence. Though rare, gastric schwannomas should be included in the differential diagnosis of submucosal gastric tumors because the correct identification of this tumor type helps in proper management and evasion of unnecessary extensive surgery.