Gastrointestinal manifestations of type 1 neurofibromatosis (von Recklinghausen's disease).

Gastrointestinal involvement in von Recklinghausen's disease occurs in three principal forms: hyperplasia of the submucosal and myenteric nerve plexuses and mucosal ganglioneuromatosis which leads to disordered gut motility; gastrointestinal stromal tumours showing varying degrees of neural or smooth muscle differentiation; and a distinctive glandular, somatostatin-rich carcinoid of the periampullary region of the duodenum that contains psammoma bodies and which may be associated with phaeochromocytoma. This review describes the histopathological features of these lesions and discusses potential pitfalls in their differential diagnosis. Their accurate identification has significant implications for clinical management and may even provide the first pointer to the diagnosis of neurofibromatosis.