[Tumor of the gastrointestinal autonomic nervous system (GAN-tumor or plexus sarcoma)]

GAN-tumors or plexosarcomas, first described by Herrera et al. in 1984, are uncommon neurogenic stromal spindle cell tumors of the intestinal tract mainly located in the stomach and the small intestine. The distinctive immunohistochemical pattern is the positive staining for vimentin and neuron-specific-enolase. Ultrastructural features are neuron-like cells with interdigitating cytoplasmic processes, dense-core neurosecretory granules, the lack of basement membranes and the presence of interstitial skeinoid fibers. Pain, chronic and acute bleeding are the most frequent but not specific symptoms and the diagnostic delay is reflected by a large average diameter of these tumors. For even smaller tumors and those with a low mitotic rate may metastasize, GAN-tumors must be considered malignant and need a radical surgical resection.