Epithelial Neoplasms

Abstract

Clinical: The terminology used to describe epidermal nevi can be very confusing as some terms include malformations of the adnexal epithelium, or are based on the main hamartomatous constituent whether keratinocyte, sebaceous, eccrine, or pilar. Our definition will focus on the keratinocyte derived epidermal nevi which occur clinically in three different varieties: (nevus verrucosus-single or multiple localized lesions, nevus unius lateris-more severe unilateral linear distribution that does not cross midline, ichthyosis hystrix-the most extreme form involving a bilateral or generalized distribution). All epidermal nevi are present at birth, or present early in childhood, as discrete yellow, tan or brown verrucous papules or plaques. Nearly 1 and 1,000 births are affected without any racial or gender predilection. The neck, trunk and extremities are most commonly involved. Lesions can be small or extensive in their involvement. Several lesions have been found arising in association with epidermal nevi including but not limited to syringocystadenoma papilliferum, basal cell carcinoma, squamous cell carcinoma, keratoacanthoma, nevus sebaceous. Important syndromes associated with epidermal nevi have been identified. The term ‘epidermal nevus syndrome’ refers to epidermal nevi with associated with neurological (i.e. seizures, learning disability), cardiac (i.e. arrhythmia), ocular (i.e. cataracts) or skeletal abnormalities (i.e. rickets, limb hypertrophy). Several other distinct syndromes associated with epidermal nevi have been made: nevus comedonicus syndrome, Schimmelpenning syndrome (actually nevus sebaceous syndrome), Becker’s nevus syndrome, congenital hemidysplasia with ichthyosiform nevus and limb defects (CHILD) syndrome, Proteus syndrome and phakomatosis pigmentokeratotica.