[9] One individual with another rare genetic disease that has similarities to tuberous sclerosis, the Birt-Hogg-Dube syndrome, has also been reported to have typical KT findings.

They often develop after puberty; increase in number over time; more frequently occur in the toenails than fingernails (the most common sites are on the big toe and thumb); are generally 5 to 10 mm in length but occasionally grow to far larger sizes;[4] and may be or become disfiguring, painful, and/or incapacitating.

[4] Microscopic histopathological analyses of KTs commonly reveal a lesion with epidermal acanthosis (i.e. thickening of the skin), hyperkeratosis (i.e. thickening of the outermost layer of the epidermis), and skin features typical of angiofibroma viz., spindle-shaped or star-shaped fibroblasts and ectatic blood vessels in a dense collagen fiber connective tissue background.

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.

[12] A small number of cases in individuals including those that do not have tuberous sclerosis may develop KTs as reactions to local traumas.

[4] The treatment of KTs has varied depending on their size, numbers, locations, symptoms, damage to tissues, and disfiguring effects.