A 6-years-old boy presented with multiple dark, raised lesions all over the body since 1 year (Fig. 1a). The disease began with discrete hyperpigmented hyperkeratotic papules over the knee and elbows which later progressed to involve the preauricular region, ear lobe, neck, both flexor and extensor aspect of upper limbs and lower limbs and buttocks (Fig. 1b). There was history of photo-exacerbation of the lesions. The child complained of pruritus and difficulty in sitting due to pain because of multiple hyperkeratotic lesions over the buttocks. There was presence of palmar pits. Oral mucosa and nails were normal. His 4-year-old sibling also presented with similar lesions over the knees and elbows. A clinical diagnosis of Darier-White disease was made. Histopathological examination from punch biopsy of a lesion showed acantholysis along with classical dyskeratosis and hyperkeratosis in the epidermis.

(a)	(b)
Fig. 1 Multiple hyperkeratotic lesions including (a) knees and elbows, and (b) buttocks.

Darier-White disease or keratosis follicularis is said to occur as a result of mutation in the ATP2A2 gene located on chromosome 12q23-24.1, responsible for coding sarco/endoplasmic reticulum calcium ATPase type 2 (SERCA2). It is characterized clinically by hyperkeratotic papules distributed mostly on the seborrheic areas of the body. Nail involvement is characterized by V-shaped nicking at the distal aspect of the nail bed, longitudinal red and white alternating bands, and subungual hyperkeratosis. Mucosal membrane involvement may occur as white papules on the buccal mucosae, palate, and gingiva with a cobblestone appearance. Palmoplantar involvement usually presents as discrete, punctate keratoses that appear as small, hyperkeratotic papules or small, centrally depressed pits. In flexures like axilla and groin, the lesions may become large exuberant growth. They may get infected due to constant maceration resulting in malodorous purulent discharge. Heat, sweat, humidity, sunlight, oral corticosteroids and mechanical trauma have been reported to exacerbate this condition.