Brief communication Photoaggravated pityriasis rubra pilaris G. Evangelou 1 , S. R. Murdoch 2 , I. Palamaras 1 , L. E. Rhodes 1 1 Photobiology Unit, Dermatological Sciences, University of Manchester, Hope Hospital, Manchester, UK, and 2 The Princess Royal Hospital, Telford, UK Pityriasis rubra pilaris (PRP) is a rare papulosqua- mous condition with an estimated incidence of one in 35 000 to one in 50 000. Psoralen and ultraviolet A (UVA) therapy has been used in its treatment but some patients are reported to be clinically photosensitive. We describe the photoinvestigation of a patient with PRP in whom sensitivity to broadband UVA was demonstrated. Key words: photoaggravation; pityriasis rubra pilaris; ultraviolet – A. A 71-year-old man was referred to the photobiol- ogy unit with a history of an intensely pruritic rash following a summer holiday in Ireland 1 year previously. The rash affected principally the sun- exposed areas, i.e. his arms, face, neck and upper chest, but continued over the winter months. The patient was aware that sunlight aggravated his condi- tion, becoming more prominent 8–12 h following ex- posure. It could be provoked by light transmitted through window glass. There was no family history of photosensitivity, atopy or other skin disorders. He was of sun-reactive skin type II. Topical steroids had not controlled his problem. On examination there was a widespread well-demarcated orange–red scaly rash with islands of normal skin (Fig. 1) affecting the face, V of chest, trunk, arms and legs, and with thicker scaly plaques in the scalp. The rash extended over the back and down to the buttocks but the eruption was markedly worse on sun-exposed areas. There was also nail involvement with subungual hyperkeratosis, prominent ectropion and mild plantar hyperkeratosis. Monochromated light testing (Oriel Ltd., Surrey, UK) to narrow bands of ultraviolet B (UVB) (300 Æ 5 nm), ultraviolet A (UVA) (320 Æ 10, 330 Æ 10, 350 Æ 20, 370 Æ 20 nm) and visible light (400 Æ 20, 500 Æ 20, 600 Æ 20 nm) showed normal erythemal thresholds. The patient received three consecutive daily challenges of 20 J/cm 2 of broadband UVA to previously uninvolved skin on his left forearm. This provoked an erythema with scaly topped papules very similar to his coexisting eruption (Fig. 2a). The same provocation challenge was performed again 4 months later, producing a rash of the same morphology. Biopsy of his naturally occurring rash revealed mild hyperkeratosis with prominence of the granular layer, acanthosis and a mild perivascular lymphocytic infil- trate, while biopsy from the UVA-induced rash was similar, showing hyperkeratosis, hypergranulosis and acanthosis (Fig. 2b). Although non-specific, the his- tological features of both biopsies were consistent with the diagnosis of pityriasis rubra pilaris (PRP). Full blood count, ESR, and routine biochemistry were all normal. Direct immunofluorescence, porphyrin and autoantibody screens were negative. Discussion We conclude that this patient’s underlying disorder is PRP with associated UVA photosensitivity. He ex- hibited features of type I PRP (classical adult form), with an extensive erythema with areas of normal skin, spreading in a cephalo-caudal direction (1). Suppor- tive diagnostic features were follicular plugging with perifollicular erythema, plantar and scalp involvement and ectropion. The involvement of exposed more than unexposed skin and worsening in the summer months, as well as the provocation by artificial UVA irradia- tion, is in keeping with a photoaggravated rash. A review by Griffiths (1) reported that improvement of PRP could occur in the summer in some patients, while sunlight could also aggravate the condition. Davidson et al. (2) reported in a series of 57 cases of PRP, that 15 patients (26%) showed exacerbation in the summer months. One previous patient with PRP Photodermatol Photoimmunol Photomed 2005; 21: 272–274 Blackwell Munksgaard Copyright r Blackwell Munksgaard 2005 272