A CASE OF GASTROINTESTINAL STROMAL TUMOR OF THE STOMACH WITH IMMUNOHISTOCHEMICAL CHARACTERISTICS OF GASTROINTESTINAL AUTONOMIC NERVE TUMOR.

The case of a 95-year-old Japanese female with a giant intramural tumor located in the upper third of the stomach is reported. A preoperative study using an endoscopic examination and gastrointestinal series revealed a large submucosal tumor with a deep concavity in the center of the surface accompanied by continuous bleeding. The tumor was removed by a minimal laparotomy instead of laparoscopic surgery because of its large size (8 × 7 × 6 cm). Its tissues were sampled, and examined by light microscopy, immunohistochemistry and electron microscopy. The tumor was vaguely encapsulated but had foci of partial infiltration of the capsule. It was comprised of spindle cells with severe nuclear pleomorphism. The mitotic count was four per 50 high-power fields. The tumor was stained strongly positive for vimentin, CD 34 and c-Kit, and weakly positive for neuron-specific enolase; had fine granular cytoplasmic stainings for synaptophysin; and was negative for cytokeratins, smooth muscle actin and S-100 protein. These immunohistochemical results strongly suggest that this tumor was a gastrointestinal autonomic nerve tumor (GANT); the ultrastructural findings, however, had no electron microscopic characteristics of the GANT. [ABSTRACT FROM AUTHOR]