|
|
|
Neurofibromatosis I (von Recklinghausen’s Disease)
|
- Syndrome: autosomal dominant inheritance related to the NF-1 gene on chromosome 17; the gene codes for neurofibromin which may play a role in modulating cell growth.
- Clinical: Patients have café-au-lait macules, neurofibromas (multiple or plexiform), optic glioma, Lisch nodules (iris hamartomas), etc. etc. etc.
- Localized neurofibromas in NF-1 look just like normal neurofibromas, but there are more of them (multiple)
- Plexiform neurofibromas are pathognomonic of NF-1, but they must be macroscopically plexiform (classical “bag-of-worms” appearance.); can have hyperpigmented skin overlying the neurofibroma
- Low power exam shows numerous nerve branches going in and out of the plane of section (shown on left)
- Other histologic features are just like solitary neurofibroma (wavy nuclei, collagen strands, myxoid material).
- Nuclear pleomorphism is not diagnostic of malignancy
- Mitoses are indicative of malignant degeneration
- Diffuse neurofibromas look like a plaque-like thickening of the skin and are most common in the head and neck; Histologic features are the same as for solitary neurofibromas; malignant degeneration is rare.
- Treatment: if malignant degeneration occurs, radical surgery is definitely indicated (but prognosis is poor: less than 20% survive 5 years.)
|
|
)
)