Phakomatosis pigmentokeratotica

Phakomatosis pigmentokeratotica is a rare neurocutanous condition characterized by the combination of an organoid sebaceous nevus and speckled lentiginous nevus. It is an unusual variant of epidermal naevus syndrome. It was first described by Happle et al. 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.

Signs and symptoms
Phakomatosis pigmentokeratotica consists of a speckled lentiginous naevus arranged in a checkerboard pattern and an organoid (epidermal) naevus associated with sebaceous differentiation. 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.

Causes
Phakomatosis pigmentokeratotica is brought on by a multipotent progenitor cell's postzygotic HRAS mutation.