Photosensitive pityriasis rubra pilaris

Pityriasis rubra pilaris (PRP) is a rare, chronic papulosquamous skin disorder. The skin lesions rarely have a predilection to sun-exposed areas although it is known that natural sunlight and phototherapy can exacerbate PRP [1–4]. We present a case of a patient suffering from pityriasis rubra pilaris with photoexposed distribution and photosensitivity exclusively to UVB objectively detected by phototesting, successfully treated with methotrexate. A 43-year-old man of Polish origin with no concomitant diseases was referred to our Department with a 3-week history of skin lesions with a predilection to sun-exposed areas. Medical history was unremarkable. The skin lesions occurred after excessive sun exposure. The patient was initially treated in the Outpatient Clinic with methylprednisolone in a dose of 32 mg/day and topical glucocorticoids with no clinical effect. On admission to the Clinic the patient presented extensive, confluent erythrosquamous and annular skin lesions, mostly on the skin of upper limbs, shoulders, trunk, upper back, neck and face. The peripheral blood laboratory tests showed no abnormalities. HCV antibodies, HBs antigen, HIV Ag/Ab and anti-nuclear antibodies tests were negative. Because of the unspecific clinical presentation clinically suggesting subacute cutaneous lupus erythematosus (SCLE) we performed phototesting with UVA and UVB on the perilesional skin. Phototesting showed the initial minimal erythema dose (MED) at 0.07 J/cm2 after 24 h and after 48 h in all UVB test fields photoreproduction was observed (Figure 1). After 3 days of hospitalization we observed follicular papules on thighs and abdomen, islands of normal skin and orange, hyperkeratotic plaques with extensive desquamation on feet and hands. The clinical presentation was consistent with classical adult onset PRP (type 1) (Figures 2 A, B). The lesional histopathological examination showed perifollicular parakeratosis and acanthosis (Figure 3). The acitretin therapy in a dose of 25 mg twice a day was initiated with progressive improvement, but after a gradual dosage reduction to 20 mg/day the skin lesions started to exacerbate. Moreover, the patient suffered from depressed