Gastrointestinal and retroperitoneal manifestations of type 1 neurofibromatosis.

Type 1 neurofibromatosis (NF1) is a genetic disease characterized by neoplastic and not neoplastic disorders, involving tissues of neuroectodermal or mesenchymal origin. The mainly involved districts are skin, central nervous system, and eye, and there is a wide range of severity of clinical presentations. Abdominal manifestations of NF1 comprehend five categories of tumors: neurogenic with neurofibromas, malignant peripheral nerve sheath tumors and ganglioneuromas, neuroendocrine with pheochromocytomas and carcinoids, non-neurogenic gastrointestinal stromal tumors, i.e., GISTs, and embryonal tumors and miscellaneous. Early diagnosis of these abdominal manifestations is very important given the risk of malignancy, organic complications such as in the case of pheochromocytomas or hemorrhagic-obstructive complications such as in the case of the tumors of the gastrointestinal tract (GISTs and neurofibromas). The importance of an annual clinical evaluation on the part of a multidisciplinary pool of clinicians in highly specialized centers allows early detection of complications and of neoplastic transformation.