Neurofibromatosis type 1

**Definition:** Neurofibromatosis type 1 (NF1) is an inherited, multi-system, neurocutaneous disorder that predisposes to the development of benign and malignant tumours. Two of the following criteria are required to diagnose NF1: six or more café au lait patches, neurofibromas, i.e. peripheral nerve sheath tumours manifesting as cutaneous, sub-cutaneous or plexiform lesions, skin-fold freckling, two or more iris Lisch nodules, an optic pathway glioma, a specific bony dysplasia (thinning of the long bone cortex, sphenoid wing dysplasia), an affected first-degree relative.

**Inclusions:** - von Recklinghausen disease