Unusual rapidly growing gastric myxoid neurofibroma: a case report.

A 62-year-old man was first found to have a gastric tumor in the fornix during a routine health examination 16 months previously. The case was not associated with von Recklinghausen's disease. Initially, the tumor was approximately 4 mm in diameter, but grew very rapidly to 20 mm in 13 months, and to 30 mm in the following month, without manifesting clinical symptoms. Malignancy was suspected because of the rapid growth and the endoscopic findings: a rough-granular elevated lesion with a wide stalk, and with erosions and mucus on its surface. Although endoscopic biopsy was done several times, the routine histological examinations were inconclusive. Endoscopic resection was therefore carried out. Examination of the resected specimen showed that the main elements consisted of wavy, long-spindled cells, which crossed irregularly, and whose interstitium was myxomatous. Immunohistochemically the specimen showed strongly positive reaction for S-100 protein and positive reaction for neuron specific enolase (NSE). Based on these immunohistochemical findings, a final diagnosis of gastric myxoid neurofibroma was made, which showed rapid growth due to myxomatous change. The patient showed a good postoperative course and no recurrence has been recognized by follow-up endoscopy.