Pityriasis rubra pilaris: a rare inflammatory dermatosis

摘要

An 18-year-old Caucasian woman presented with a 2-week history of a pruritic rash commencing on the face and spreading distally to the trunk and limbs. There were no associated systemic symptoms. Her medical history was unremarkable and there was a family history of hypothyroidism. Physical examination revealed extensive confluent scaly erythema with islands of sparing on the trunk and scaling of the scalp. There was hyperkeratotic plugging of the hair follicles ( and  ). There was a waxy orange keratoderma affecting the palms and soles with associated painful fissuring ( ). A clinical diagnosis of pityriasis rubra pilaris (PRP) was made. Histopathology of involved skin showed focal parakeratosis and orthokeratosis alternating in both horizontal and vertical directions with an underlying perivascular inflammatory infiltrate. The patient had a raised thyroid stimulating hormone (TSH) and normal T4 indicative of subclinical hypothyroidism. Treatment for her skin was initiated with methotrexate and titrated to a dose of 15 mg weekly. There was complete remission at 16 weeks. This case fits the description of classical adult-type PRP.