Neurofibroma classification
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Shanshan Cen, M.D. [2]
Overview
Classification
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 neurofibroma
Anatomy
Dermal neurofibromas (sometimes referred to as cutaneous neurofibromas) originate in nerves in the skin. Three kinds are distinguished:
- Discrete cutaneous neurofibromas: Sessile or pedunculated masses on the skin, which are fleshy and non-tender, and can vary in size.
- Discrete subcutaneous neurofibromas: Lie below and look like bumps on the skin, which can sometimes be tender.
- Deep nodular neurofibromas: Involving tissues and organs underneath the dermis, but otherwise resembling cutaneous and subcutaneous neurofibromas.
Age of onset
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.
Medical complications
Dermal neurofibromas can lead to stinging, itching, pain and disfiguration.
There is no evidence of malignant transformation.
Plexiform Neurofibroma
Anatomy
Plexiform neurofibromas can grow from nerves in the skin or from more internal nerve bundles, and can be very large. Internal plexiform neurofibromas are very difficult to remove completely because they extend through multiple layers of tissue and the attempt would damage healthy tissue or organs.
Age of onset
Plexiform neurofibromas occur earlier in life and are thought to be congenital defects.[1]
Medical complications
Plexiform neurofibroma can cause disfigurement, neurological and other clinical deficits.
Plexiform neurofibromas have the potential to cause severe clinical complications if they occur in certain areas.[2]
About 10% of plexiform neurofibromas undergo transformation into a malignant peripheral nerve sheath tumor (MPNST).[3] The formation of malignant cancers from neurofibromas is associated with the loss of expression of the CDKN2A or TP53 gene in non-myelinating Schwann cells that also exhibit biallelic inactivation of the NF1 gene.
References
- ↑ "Case Based Pediatrics For Medical Students and Residents: Chapter XVIII.11. Neurofibromatosis", by Vince K. Yamashiroya, MD. August, 2002. Department of Pediatrics, University of Hawaii John A. Burns School of Medicine.
- ↑ Kluwe L, Hagel C, Mautner V (April 2007). "Neurofibroma".
- ↑ Mautner VF, Friedrich RE, von Deimling A, Hagel C, Korf B, Knöfel MT, Wenzel R, Fünsterer C. (2003). "Malignant peripheral nerve sheath tumours in neurofibromatosis type 1: MRI supports the diagnosis of malignant plexiform neurofibroma". American Journal of Pathology. 45 (9): 618–25. doi:10.1007/s00234-003-0964-6. PMID 12898075.