A 10-year-old boy presented with a solitary pruritic skin lesion near the right eye which was present since 4 months. To start with, there was a small elevated lesion with mild itching which gradually increased in number and coalesced. Cutaneous examination revealed a well circumscribed 3cm X 1.5cm plaque with lichenification towards the centre. The margin of the lesion was hypopigmented whereas the centre was hyperpigmented. Fine scales were noted in the periphery of the lesion (Fig. 1). No similar lesion was present elsewhere in the body; hairs, nails and mucosae were normal. Biopsy showed epidermal spongiosis with a dermal, perivascular, mainly mononuclear cell infiltrate and edema. A diagnosis of plaque-type polymorphous light eruption was made.

Fig. 1 Solitary well-circumscribed plaque on face.

Polymorphous light eruption is an acquired sunlight-induced dermatosis, particularly at temperate latitudes, affecting 10-20% of the population. It is usually characterized by an itchy, erythematous, symmetrically distributed, papulovesicular rash, on some exposed areas within hours of exposure to ultraviolet radiation. Classical histopathological findings include epidermal spongiosis with a dermal, perivascular, mainly mononuclear cell infiltrate and edema. It usually responds to broad-spectrum sunscreens and oral or topical steroids. Prophylactic low-dose immunosuppressive phototherapy in spring may be given for frequent episodes. Close clinical differentials are Hansen’s disease (presence of hypoesthesia or anesthesia) and psoriasis (silvery white scales over an erythematous plaque).