<unk> s have been subdivided into two broad categories: dermal and plexiform. Dermal<unk> s are associated with a single peripheral nerve, while plexiform<unk> s are associated with multiple nerve bundles. According to the World Health Organization classification system, dermal and plexiform<unk> s are grade I tumors. Plexiform<unk>  are more difficult to treat and can transform into malignant tumors. Dermal<unk>  do not become malignant. Dermal<unk>  Anatomy Dermal<unk> s (sometimes referred to as cutaneous<unk> s) originate in nerves in the skin. Three kinds are distinguished: * Discrete cutaneous<unk> s: Sessile or pedunculated masses on the skin, which are fleshy and non-tender, and can vary in size. * Discrete subcutaneous<unk> s: Lie below and look like bumps on the skin, which can sometimes be tender. * Deep nodular<unk> s: Involving tissues and organs underneath the dermis, but otherwise resembling cutaneous and subcutaneous<unk> s. Age of onset Dermal<unk> s typically arise in the teenage years and are often associated with the onset of puberty. In people with<unk> tosis Type I, they tend to continue to increase in number and size throughout adulthood, although limits exist as to how big they get, and cases progress at highly variable rates. Medical complications Dermal<unk> s can lead to stinging, itching, pain, and disfigurement. No evidence of malignant transformation has been found. Dermal<unk>  in a person whose lesions first appeared when he was a teenager Plexiform<unk>  Anatomy Plexiform<unk> s can grow from nerves in the skin or from more internal nerve bundles, and can be very large. Internal plexiform<unk> s 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 Image of<unk>  showing myxoid appearance Plexiform<unk> s occur earlier in life and are thought to be congenital defects. Medical complications Plexiform<unk>  can cause disfigurement, neurological, and other clinical deficits. Plexiform<unk> s have the potential to cause severe clinical complications if they occur in certain areas. About 10% of plexiform<unk> s undergo transformation into a malignant peripheral nerve sheath tumor. The formation of malignant cancers from<unk> s is associated with the loss of expression of the CDKN2A or TP53 gene in nonmyelinating Schwann cells that also exhibit biallelic inactivation of the<unk> 1 gene.
Neurofibroma
Palisaded encapsulated neuroma
Neuroma
Hemangioblastoma
Ameloblastoma
Ganglioneuroma
Ganglion cyst
Brenner tumour