Juvenile-like (inflammatory/hyperplastic) mucosal polyps of the gastrointestinal tract in neurofibromatosis type 1

Aims: Diffuse neurofibromatosis/ganglioneuromatosis, solitary/plexiform neurofibroma, periampullary carcinoids and gastrointestinal stromal tumour (GIST) are the main gastrointestinal manifestations of neurofibromatosis type 1 (NF-1, von Recklinghausen disease). Inflammatory (juvenile-like) polyps have not been recognised to date as specific gastrointestinal (GI) manifestations of NF-1.

Methods and results: We describe four males aged 23-65 years with NF-1 and inflammatory (juvenile-like) gastrointestinal polyps, and review the literature for similar cases. Two patients had single polyps (sigmoid colon and antrum, respectively), one had two polyps (left colon), and one had three polyps (distal oesophagus and colon). Histological appearances were variable, ranging from juvenile-like to granulation tissue-rich, predominantly inflammatory and hyperplastic. Three lesions showed obliterative vasculopathic changes. None had neurofibromatous or ganglioneuromatous polyps. A review of the literature disclosed 11 similar cases. Most patients presented with severe gastrointestinal symptoms and/or anaemia.

Conclusions: NF-1-associated inflammatory polyps probably represent specific GI manifestations of this disorder, and should be considered, particularly in patients with GI symptoms. They should be distinguished from inflammatory fibroid polyps and from juvenile-like changes associated with ganglioneuroma/ganglioneuromatosis and neurofibroma/neurofibromatosis. Their aetiology remains obscure, but different mechanisms, including NF-1 inactivation, NF-1-associated vasculopathy, and localised mucosal prolapse/damage caused by motility disorders, might be involved.