A 12-year-old girl presented with multiple, asymptomatic, annular lesions over right side of upper chest and right forearm for last 5 years. Initially, few small brown coloured papules appeared over the chest which gradually increased in number and size to attain the present status. The lesions were asymptomatic from the beginning. There was no history of similar episodes in the past or in the family, and no history of any skin lesions at birth. On examination, multiple skin coloured annular plaques (1.5-2 cms × 3-7 cms in size) with a well-demarcated raised, thready margin with central hypopigmentation and atrophy were found. They were arranged in a linear configuration and unilaterally over right side of upper chest and right forearm (Fig.1 and 2). The lesions had a tendency of peripheral extension and central clearing. Mucosa, scalp and nails were spared. Biopsy was done from one of the lesions and on histopathological examination, hyperkeratosis, cornoid lamella with perivascular dermal infiltrates were seen and central part of the lesion showed atrophy. Biopsy findings confirmed it to be a case of "unilateral linear porokeratosis". She has been prescribed topical retinoids and she is under regular follow-up because this variant of porokeratosis is highly prone to develop malignancy.

Fig. 1 Linear arrangement of multiple annular plaques.

Fig. 2 Skin lesions showing demarcated raised irregular margins with central hypopigmentation.