Making the Right Diagnosis

There are two different types of neurofibromatosis, called neurofibromatosis type 1 and neurofibromatosis type 2. Each disorder is distinct and has a unique set of medical problems and concerns. It is important for you and the physicians who care for you to recognize which form of neurofibromatosis you have.

Diagnosing Neurofibromatosis type 1 (NF1)

Neurofibromatosis type 1 (NF1) is the more common neurofibromatosis condition and affects ten times more people than NF2. The diagnosis of NF1 is made when an individual has two or more of the following findings:

  • At least six cafe-au-lait macules over 5 mm in greatest diameter before puberty or six cafe-au-lait macules over 15 mm in greatest diameter after puberty
  • Two or more neurofibromas of any type or one plexiform neurofibroma
  • Multiple freckles in the axillary (armpit) or inguinal (groin) regions
  • A distinctive bone abnormality involving the eye socket or arm/leg bones
  • A tumor on the optic nerve located in the brain called an optic glioma
  • Two or more Lisch nodules on slit-lamp examination
  • A parent, sibling, or child with NF1

Diagnosing Neurofibromatosis type 2 (NF2)

Neurofibromatosis type 2 (NF2) is sometimes more difficult to diagnose, since most of the features of this disorder may require imaging by CT or MRI scan to detect.

Unlike NF1, people with NF2 have few skin abnormalities and do not typically have café-au-lait macules, freckling, or Lisch nodules. Most of the signs of NF2 are tumors that grow on nerves and in the brain. The diagnosis of NF2 is made when an individual has the following findings:

  • Schwannomas on both 8th cranial (vestibular) nerves OR
  • A parent, sibling, or child with NF2 plus:

» One vestibular schwannoma in a person less than 30 years of age OR

» Any two of the following: meningioma, glioma, schwannoma, juvenile cataracts

The diagnosis of NF2 should be suspected when an individual has the following findings:

  • One vestibular schwannoma in a person less than 30 years of age in combination with either a meningioma, schwannoma, glioma, or juvenile cataracts
  • More than one meningioma in a person less than 30 years old with a vestibular schwannoma
  • More than one meningioma in a person with a glioma, schwannoma, or juvenile cataracts