Which syndromes are associated with epidermal nevi (EN)?

Updated: Mar 26, 2020
  • Author: Robert A Schwartz, MD, MPH; Chief Editor: William D James, MD  more...
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Answer

Six different syndromes with epidermal nevi as part of them have been delineated. These include (1) Proteus, (2) congenital hemidysplasia with ichthyosiform nevus and limb defect, (3) phakomatosis pigmentokeratotica, (4) sebaceous nevus, (5) Becker nevus, and (6) nevus comedonicus [6] syndromes.

Phacomatosis pigmentokeratotica is characterized by the presence of multiple organoid nevi with sebaceous differentiation, a speckled lentiginous nevus, and skeletal and neurologic abnormalities. [7] It may or may not be associated with extracutaneous involvement. One patient with it developed basal cell carcinoma, syringocystadenoma papilliferum, and trichilemmoma within the nevus sebaceous. [8] In a study of one affected family, phacomatosis pigmentokeratotica was found to be caused by a postzygotic HRAS mutation in a multipotent progenitor cell. [9]

The spectrum has been expanded with the description of linear Cowden nevus as a new distinct epidermal nevus. [10] This nonorganoid epidermal nevus is probably due to loss of heterozygosity, occurring at an early developmental stage in an embryo with a germline PTEN mutation, giving rise to Cowden disease. The combination of nevoid hypertrichosis, diffuse lipoatrophy, and epidermal nevus has been suggested as a possible new epidermal nevus syndrome. [11] Thus, the epidermal nevus syndrome may be best viewed as a heterogeneous congenital disorder that includes both the keratinocytic epidermal nevus syndrome and sebaceous nevus syndrome. [12] An individual patient may have the same postzygotic HRAS and KRAS gene mutations and be evident clinically with distinct features.


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