What is the pathophysiology of epidermal nevus syndrome (ENS)?

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

Epidermal nevi arise from pluripotential germinative cells of the basal layer of the embryonic epidermis.

Inflammatory linear verrucous epidermal nevus is distinct from psoriasis; however, they may share some common pathogenic pathways. These pathways are probably mediated by interleukin 1, interleukin 6, tumor necrosis factor-alpha, and intercellular adhesion molecule-1.

Epidermal nevus syndrome–associated skeletal disease focal bone defects may manifest as fibrous dysplasia, even without the typical radiographic or histopathologic findings of fibrous dysplasia. [13] A patient had elevated circulating fibroblast growth factor 23 (FGF-23) levels with no activating mutations. This focal skeletal disease may be a source of FGF-23 in persons with epidermal nevus syndrome and thus may be a clue to its pathogenesis.

A bilateral, systematized epidermal nevus syndrome patient was described with cerebral involvement caused by a mosaic FGFR3 mutation, possibly representing a distinct entity within the group of epidermal nevus syndromes. [14] Other mutations of FGFR3 have been described in keratinocytic epidermal nevus syndrome. [15] A mosaic KRAS mutation has also been documented. [16] A somatic KRAS mutation was documented in an infant with linear nevus sebaceous syndrome associated with lymphatic malformations. [17]

The Schimmelpenning-Feuerstein-Mims syndrome, which is composed of a craniofacial nevus sebaceus, seizures, developmental delay, and ocular and skeletal abnormalities, is a sporadic condition hypothesized to result from mosaicism involving a lethal autosomal dominant gene. [18] It has been described in severely affected discordant monozygotic twins, supporting the concept of a postzygotic mutation.


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