<unk>  (KT), also commonly termed periungual angiofibroma, is a subtype of the angiofibromas. Angiofibromas are benign papule, nodule, and/or tumor lesions that are separated into various subtypes based primarily on the characteristic locations of their lesions. KTs are angiofibromas that develop in and under the toenails and/or fingernails. KTs were once considered as the same as another subtype of the angiofibromas viz., acral angiofibromas. While the literature may still sometimes regard KTs as acral angiofibromas, acral angiofibromas are characteristically located in areas close to but not in the toenails and fingernails as well as in the soles of the feet and palms of the hands. KTs are here regarded as distinct from acral angiofibromas. KTs most commonly develop in individuals who have the rare genetic disease, tuberous sclerosis (a heritable neurocutaneous disorder) and uncommonly in individuals that do not have this genetic disease. 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. KTs are strictly benign (i.e. do not metastasize) but may be painful, disfiguring, and sometimes large and/or incapacitating lesions. They have often been treated by strictly local surgical resections. However, they do have a high rate of recurrence at the site of resection and therefore have been treated with various other non-invasive local measures in efforts to avoid recurrences; these other methods have also been preferred to treat numerous tumors in individuals, for cosmetic reasons, and/or to relieve tumor-induce incapacitations. Presentation== In individuals with tuberous sclerosis, KTs commonly present with multiple firm red-colored to skin-colored nodules or tumors that emanate from the proximal nail fold or, less often, proximal skin beneath the nail. 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; and may be or become disfiguring, painful, and/or incapacitating. Nearly 50% of post-puberty individuals with tuberous sclerosis have KTs. (Tuberous sclerosis is also associated with a second type of angiofibroma, adenoma sebaceum, also termed facial angiofibroma, in ~75% of cases.) Individuals presenting with KTs that do not have tuberous sclerosis commonly present with a single lesion in a nail bed. KT may also present as a recurrence of a lesion at the site where it was surgically removed. Rare cases of KTs have had a history of crushing trauma at the sites where the KTs later developed.
Koenen's tumor
Askin's tumor
Baker's cyst
Tarlov cyst
Krukenberg tumor
Bartholin's cyst
Tornwaldt cyst
Klatskin tumor