Verrucuous epidermal nevus Linear verrucuous lesions, with characteristic histopathological feature of granular degeneration of the epidermis ours the diagnosis of verrucous epidermal nevus. Epidermal nevus Epidermal nevi are hamaomas that are characterized by hyperplasia of the epidermis and adnexal structures. These nevi may be classified into a number of distinct variants which are based on clinical morphology, extent of involvement and the predominant epidermal structure in the lesion. Variants of the epidermal nevi are ? - Verrucuous epidermal nevus - Nevus sebaceous - Nevus comedonicus - Eccrine nevus - Apocrine nevus - Becker's nevus - White sponge nevus Verrucuous epidermal nevus Verrucuous epidermal ,nevus consists of hyperplasia of the surface epidermis and typically appears as verrucuous papules that coalasce to form well demarcated, skin colored to brown, papillomatous plaque. Most lesions are present at bih and develop during infancy. They enlarge slowly during childhood and generally reach a stable size at adolescence. Lesions may be localized or diffuse. Linear configurations are common especially on the limbs and may follow skin tension lines or Blaschko's lines. The salient histological features are ? Perinuclear vacuolization of the cells in the stratum spinosum and stratum granulosum. Irregular cellular boundaries peripheral to the vacuolization and increased number of irregularly :,aped large keratohyaline granules. Compact hyperkeratosis in stratum corneum. Darner white disease Autosomal dominant disease. Males and females are equally affected. Daffier white disease is not present at bih and usually begins in the first or second decade. Characteristic sites of prediliction are the face, forehead, scalp, chest and the hack (seborrhic sites). Clinical features consists of way papules and plaques in (seborrhic sites). Histology shows suprabasal acantholysis in epidermis with dyskeratotic cells. Incontinentia pigmentii X linked disease (so only seen in females) Lesions are present along the Blaschko lines, which are initially vesicular, that later on turns into verrucuous lesions and hyperpigmented stages. Common histological features are : - Hverkeratosis - Eosinophilic spongiosis of epidermis - Basal cell degeneration - Pigment incontinenti