Coexistence of Linear Porokeratosis and Disseminated Superficial Actinic Porokeratosis: A Type 2 Segmental Manifestation

Abstract

Six main clinical forms of porokeratosis are recognized: classical porokeratosis or porokeratosis of Mibelli, punc-tate palmoplantar porokeratosis, linear porokeratosis (LP), disseminated superficial porokeratosis, dissemina-ted superficial actinic porokeratosis (DSAP), and disse-minated palmoplantar porokeratosis (1). The coexistence of more than one form in a single individual is infrequent. We describe here a 48-year-old woman who had a small LP lesion since infancy and developed DSAP in her fifth decade of life.CASE REPORTA 48-year-old Caucasian woman without relevant ante-cedents presented with pale rough-surfaced lesions on her forearms and legs, first noticed 4 years previously. Over the preceding 2 years they had become pruritic, particularly during the summer, when they increased in number. She had no family history of similar le-sions. Physical examination revealed small plaques 5–10 mm in diameter on the extensor surfaces of the forearms and legs, clearly delimited, rounded or oval, with lighter-coloured and slightly atrophic centres, and a hyperpigmented keratotic outer ring. These lesions were not confluent and did not show any clear spatial organization (Fig. 1A). In the right axillary region and extending towards the inner surface of the arm, the patient showed several lesions very similar to those on the forearms and legs, but more conspicuous and confluent, arranged in a linear pattern (Fig. 1B). The patient reported that she had had these lesions from childhood. Neither palmoplantar regions nor mucosal tissues were affected. Histopathological study of the linear lesion and one of the leg plaques confirmed the diagnosis of porokeratosis. The epidermis showed a compact column of parakeratotic cells with loss of granular layer, superficial mononuclear infiltration with areas of vacuolization in the basal layer, and presence of isolated melanophages in the papillary dermis. General examination did not detect any other manifestations, and the patient’s overall health was good. Standard biochemical analyses, immunological studies and haemograms likewise did not reveal patho-logical findings. Treatment was started with topical 0.1% tretinoin, once daily for 3 months. This treatment had a modest effect, and was changed to cryosurgery, with acceptable results to date. We continue to monitor the patient at periodic intervals.DISCUSSIONIn the patient described here, the lesions had developed 4 years previously, were slightly pruritic, worsened on exposure to sunlight, and had gradually increased in number; by contrast, the linear lesion had arisen in infancy, and was asymptomatic and unchanging. On physical examination the lesions on her legs and forearms were subtle and non-evident, while the linear lesion was much more evident. The coexistence of different clinical forms of poroke-ratosis in a single individual is uncommon (2, 3). There have been a few previously reported cases of association between LP and DSAP, mostly in children and young