Neurofibroma pathophysiology
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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
Pathogenesis
- Neurofibromas arise from nonmyelinating-type Schwann cells that exhibit biallelic inactivation of the NF1 gene that codes for the protein neurofibromin.[1] This protein is responsible for regulating the RAS-mediated cell growth signaling pathway.
- 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.
- 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.
Gross Pathology
Microscopic Pathology
Genetics
About 10% of plexiform neurofibromas undergo transformation into a malignant peripheral nerve sheath tumor (MPNST).[2] 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
- ↑ Muir D, Neubauer D, Lim IT, Yachnis AT, Wallace MR. (2003). "Tumorigenic properties of neurofibromin-deficient neurofibroma Schwann cells". American Journal of Pathology. 158 (2): 501–13. doi:10.1016/S0002-9440(10)63992-2. PMC 1850316. PMID 11159187.
- ↑ 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.