Coincident occurrence of granular cell tumor of the stomach with an early gastric carcinoma.

In a 41-yr-old Japanese woman, a rare coincident lesion composed of granular cell tumor and early gastric adenocarcinoma was detected in the stomach. Beneath the poorly differentiated adenocarcinoma almost limiting to the mucosa, the granular cell tumor measuring 1.2 x 0.8 cm was spreading mainly in the submucosa without forming polypoid nodule. To the best of our knowledge, this is the first published report on this type of coincidence. Immunohistochemically, the cells of the granular cell tumor were strongly positive for S-100 protein, but negative for muscle markers (HHF 35, desmin), some of which connected with perineural Schwann cells surrounding small vessels in the submucosa. These features suggested that granular cell tumor in our case arose from Schwann cells surrounding small vessels in the submucosa of the stomach.