[Generalized linear porokeratosis limited to one side of the body].

Poroqueratosis (PQ) refers to a group of disorders of keratinization with the common histological feature of the presence of cornoid lamellae, narrow columns of parakeratosis on a focally disorganized epidermis.1 We present 2 patients with lesions compatible with linear PQ, with extensive involvement of one side of the body. The first patient was a 23-year-old man with no past history of interest. He was seen for the presence of multiple lesions that had been present for 20 years. The lesions had started to appear in the left inguinocrural region in the first year of life, affecting a progressively larger area, following a metameric pattern on the left lower limb and medial region of the left foot. At 4 years of age, when it appeared that the disorder had stabilized, he began to develop new lesions in the left scapular region and on the left upper limb, following a blaschkoid distribution. The patient noticed that no new lesions had appeared after 18 years of age. On physical examination the patient presented multiple annular lesions that became confluent, forming polycyclic and tortuous patterns. The basic lesion consisted of a central area of atrophy, occasionally verrucous, that was clearly demarcated by a peripheral hyperkeratotic border. The lesions were not infiltrated, were not adherent to the deep planes, and varied in size between 1 and 5 cm in their largest diameter. The lesions were present only on the left side of the patient’s body, following a metameric or blaschkoid linear distribution, affecting the upper and lower limbs, trunk, and genital region (Figure 1), but were not found on the face. A 5 mm biopsy that included the hyperkeratotic border and the central atrophic area was taken from a lesion on the left ankle. Central epidermal atrophy surrounded by a peripheral parakeratotic column was visible at low magnification (Figure 2). Higher magnification revealed Generalized Linear Porokeratosis Limited to One Side of the Body