Computed tomographic characteristics of gastric schwannoma

Schwannomas originate from Schwann cells of the neural sheath of peripheral nerves and most commonly occur in the head and neck or in the flexor side of the extremities.1,2 Schwannomas rarely occur in the gastrointestinal tract and the stomach is the most common gastrointestinal site. Gastric schwannomas (GSs) represent approximately 0.2% of all gastric tumors3,4 and 2% to 7% of all gastrointestinal mesenchymal tumors.5,6 Conventional schwannomas are encapsulated tumors that are generally benign and have slow growth, and malignant schwannomas are extremely rare.3,7 Schwannomas are characteristically composed of both hypercellular (Antoni type A) and hypocellular (Antoni type B) areas. In contrast, GSs are completely or predominantly composed of Antoni type A areas, which may result in different imaging features from those at other sites.8–10 GS usually presents with non-specific symptoms, epigastric pain, or black stool.11,12 Histological features of GS include a spindle cell pattern, usually with vague nuclear palisading and peritumoral lymphoid cuff, and without encapsulation.13,14 A histological diagnosis of GS can be confirmed by positive immunoreactivity for S-100 protein and negative immunoreactivity for CD117 and DOG-1.11,13,15 GS generally has a favorable prognosis, and surgical resection is considered an effective treatment. Because of a lack of specific imaging features, GSs are difficult to be distinguished from the more common submucosal tumors, such as gastrointestinal stromal tumor (GIST), before surgery. However, the treatment and prognosis are totally different between these two tumors. Therefore, the correct diagnosis of GS before surgery is important in these patients. In this study, we retrospectively studied 19 patients with GS. We evaluated CT and clinicopathological parameters to determine the characteristics of tumors and to diagnose GS accurately before surgery.