Stromal tumors of the gastrointestinal tract: myogenic or neurogenic?

Because of the recent controversy over the histogenesis of gastrointestinal stromal tumors, 170 gastrointestinal tract tumors appearing to be of smooth muscle type with routine stains were studied immunohistochemically. Five percent were positive for S-100 ("neural") protein. These findings are compared with several recent studies. We conclude that only a small minority of gastrointestinal tract stromal tumors are neurogenic and that most are probably of smooth muscle type.