A 3-year-old girl presented to us for a rough aspect of the trunk. Dermatologic examination showed multiple rough papules in the upper and lower limbs (Fig. 1a), extending to the trunk (Fig. 1b) and upper limbs with a linear arrangement, and then to the face (Fig.1c).We also found a focal palmoplantar keratoderma distributed in small islands. According to the clinical aspect of the lesions, we suspected porokeratosis that was confirmed by the skin biopsy. She was treated by acitretin (0.25 mg/kg/day) with good evolution within 3 months.

Fig.1 (a) Multiple papules in the upper limbs with a linear arrangement; (b) Multiple rough papules in the trunk; and (c) Extended lesions to the trunk and the face.

Porokeratotic eccrine ostial and dermal duct nevus (PEODDN) is a rare variant of porokeratosis due to a mutation in GJB2 gene coding for the connexin 26 junction protein. PEODDN can present as multiple hyperkeratotic or atrophic papules grouped on plaques with a blashko linear arrangement. These lesions are mainly located at the extremities and are frequently associated with a palmoplantar involvment. Proximal involvement of the extremities, the trunk and the face, as seen in this patient is very rare. The pathognomonic histological findings are characterized by cornoid lamella located in relation of a dilated sweat excretor canals and associated to vacuolated keratinocytes in the epidermic invagination. Differential diagnoses include Linear porokeratosis, linear lichen planus, linear verrucous epidermal nevus, and linear Darier’s disease. PEODDN start at birth or in the early childhood. Clinically it resembles a comedonal nevus, but it occurs on the palms and soles where pilosebaceous follicles are normally absent. Treatment options include dermocorticoids, topical calcipotriol, cryotherapy, CO2 laser, photodynamic therapy and retinoids.