GISTs in neurofibromatosis I

Neurofibromatosis I is associated with a range of tumour, including (plexiform) neurofibromas phaeochromocytoma, and, in the gastrointestinal tract, neuronal hyperplasia (neuromas), ampullary carcinoid and gastrointestinal stromal tumours. About 1.5% of all GISTs occur in the context of neurofibromatosis. The GISTs that occur in the context of neurofibromatosis seem to have a low incidence of KIT mutation.

Most GISTs in neurofibromatosis occur in the small intestine:

	Stomach	11
	Duodenum	101
	Jejunum	141
	Ileum	41
	Small bowel NOS	161

Histopathology

Many cases show Cajal cell hyperplasia in the small intestine. Some cases show complex Schwann cell proliferation with the myenteric plexus, the proliferating cells being positive for S-100.

Immunohistochemistry

	CD117	31/311
	CD34	23/291
	SMA	7/311
	S-100	7/191
	Desmin	0/251

Differential diagnosis

Schwannoma is rare in the gastrointestinal tract in neurofibromatosis. Note that GISTs are commonly positive for S-100.
Leiomyoma or leiomyosarcoma

References

1 Miettinen M, Fetsch JF, Sobin LH, et al. Gastrointestinal Stromal Tumors in Patients With Neurofibromatosis 1: A Clinicopathologic and Molecular Genetic Study of 45 Cases. Am J Surg Pathol 2006; 30:90-96

This page last revised 28.1.2006.