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Neurofibromatosis 1 : Diagnostic Criteria

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The diagnosis of neurofibromatosis 1 requires the presence of at least 2 or more of the following 7 diagnostic criteria as proposed by NIH. The diagnosis may be delayed until late childhood or adolescence due to the late appearance of some of these signs.

  • Six or more cafe-au-lait spots >5 mm in size (prepubertal) and >15 mm in size postpubertal
  • Axillary or inguinal freckles (>2 freckles)
  • Two or more typical neurofibromas or one plexiform neurofibroma
  • Optic Nerve Glioma
  • Two or more iris hamartomas (Lisch nodules)
  • Sphenoid dysplasia or typical long-bone abnormalities such as pseudoarthrosis
  • First-degree relative (eg parent, sibling, offspring) with NF 1
There are several variant forms of neurofibromatosis, including segmental neurofibromatosis (neurofibromas are localized to one area/segment of body; caused by somatic mosaicism of NF1 mutations); Gastrointestinal NF; Familial Spinal NF; Familial cafe-au-lait spots.

The image shows a plexiform neurofibroma of brachial plexus in a young female with NF1. The involved nerve trunks form a thickened, tortuous mass resembling "a bag of worms." Image copyright:

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