loss-of-function mutations in one of the two normally paired TSC1 or one of the two normally paired TSC2 tumor suppressor genes. As a part of their functions, the TSC1 and TSC2 tumor suppressor genes act to suppress the abnormal growth of cells by contributing to the suppression of the mammalian target of rapamycin (i.e. mTOR) protein that promotes cell growth and proliferation. Inactivation of one of the TSC1 or TSC2 genes appears responsible for unleashing mTor and thereby promoting the growth of the many strictly benign lesions, including KTs, that develop in individuals with tuberous sclerosis. mTOR is inhibited by rapamycin, a drug which has been used as a topical application to successfully treat a few cases of Koenens tumors.A small number of cases in individuals including those that do not have tuberous sclerosis may develop KTs as reactions to local traumas. Treatment
The treatment of KTs has varied depending on their size, numbers, locations, symptoms, damage to tissues, and disfiguring effects. Excision may be the treatment of choice for surgically accessible lesions. However, following surgical removal, KTs have a high rate of local recurrence, particularly in cases where the lesions are not completely removed. Other treatment methods, which may be used in combination with surgical removal and/or with each other include: carbon dioxide-based laser vaporization; electrocauterization; shave excision of the tumor with phenolization (i.e.
excision of the tumor’s protruding portion followed by treatment of the proximal perionych [i.e., skin around a nail] with phenol to eradicate the root of the tumor); and in individuals with tuberous sclerosis, topical application of sirolimus, i.e. rapamycin, (1% solution). Some of the latter methods have been used in order to preserve the nail matrix and nailplate and may be ideal for younger patients with few tumors since they may leave a normal appearing nail. See also
List of cutaneous conditions
Nail anatomy


== References ==