Myxoid Perineurioma Presenting As a Gastric Polyp

A 58-year-old man presented with epigastric pain that was refractory to analgesia. Before this, he was well and did not have manifestations of type 1 neurofibromatosis. Endoscopy revealed a 0.5-cm polypoid antral lesion that was snared and removed in total. Histological evaluation showed a submucosal myxoid spindle-cell proliferation. The tumor was arranged in whorls with distinct concentricity. Within the myxoid stroma, occasional eosinophils were present together with a delicate capillary network. There was no cytological atypia, areas of hypercellularity, or necrosis. The lesion was strongly positive for epithelial membrane antigen and also positive for CD34. All other markers including S-100, desmin, and CD117 were negative. The overall morphological and immunophenotypic features of this lesion are in keeping with a myxoid gastric perineurioma. This lesion needs to be separated from an inflammatory fibroid polyp and a gastrointestinal stromal tumor.