Neurofibromas

Neurofibroma
Histopathologic image of cutaneous neurofibroma obtained by biopsy
Classification and external resources
Specialty	oncology
ICD-10	D36.1 (ILDS D36.160)
ICD-O	M9540/0-9550
DiseasesDB	23371
MeSH	D009455
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A neurofibroma is a benign nerve sheath tumor in the peripheral nervous system. In 90% of cases they're found as stand-alone tumors, while the remainder are found in persons with neurofibromatosis type I (NF1), an autosomal dominant genetically inherited disease, they can result in a range of symptoms from physical disfiguration and pain to cognitive disability. Neurofibromas arise from nonmyelinating-type Schwann cells that exhibit biallelic inactivation of the NF1 gene that codes for the protein neurofibromin. This protein is responsible for regulating the RAS-mediated cell growth signaling pathway. In contrast to schwannomas, another type of tumor arising from Schwann cells, neurofibromas incorporate many additional types of cells and structural elements in addition to Schwann cells, making it difficult to identify and understand all the mechanisms through which they originate and develop.

Neurofibromas have been subdivided into two broad categories: dermal and plexiform. Dermal neurofibromas are associated with a single peripheral nerve, while plexiform neurofibromas are associated with multiple nerve bundles. According to the World Health Organization classification system, dermal and plexiform neurofibromas are grade I tumors. Plexiform neurofibroma are more difficult to treat and can transform into malignant tumors. Dermal neurofibroma do not become malignant.

Dermal neurofibromas (sometimes referred to as cutaneous neurofibromas) originate in nerves in the skin. Three kinds are distinguished:

Dermal neurofibroma typically arise in the teenage years and are often associated with the onset of puberty. They continue to increase in number and size throughout adulthood, although there are limits to how big they get.

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