Phakomatosis pigmentokeratotica is a rare neurocutanous condition characterized by the combination of an organoid sebaceous nevus and speckled lentiginous nevus.
[3] It was first described by Happle et al.[4] It is often associated with neurological or skeletal anomalies such as hemiatrophy, dysaesthesia and hyperhidrosis in a segmental pattern, mild mental retardation, seizures, deafness, ptosis and strabismus.
[5] Phakomatosis pigmentokeratotica consists of a speckled lentiginous naevus arranged in a checkerboard pattern and an organoid (epidermal) naevus associated with sebaceous differentiation.
[6][7] Other abnormalities are prevalent; these are usually neurological or skeletal and include hemiatrophy, segmental dysaesthesia and hyperhidrosis, minor mental retardation, seizures, deafness, ptosis, and strabismus.
[5] Phakomatosis pigmentokeratotica is brought on by a multipotent progenitor cell's postzygotic HRAS mutation.