Case Presentation
A 4-year-old girl, without a prior history of eczema or psoriasis, presented with a 4-weeks history of extensive erythematous scaly eruption which started on her face and scalp, and spread rapidly to her torso and limbs ( Figure 1, A, B, E and F ). She also had well-circumscribed, red-orange, waxy plaques on the palms and soles ( Figure 1, C and D ). Her growth and psychomotor development were normal. Histopathology showed basket-like hyperkeratosis, diffuse orthokeratosis and spotted parakeratosis, and a dermal superficial perivascular lymphocytic infiltration ( Figure 1G ). The final diagnosis was pityriasis rubra pilaris.
Teaching Point
Pityriasis rubra pilaris is a rare inflammatory skin disease that affects men and women of all ages, which presents with hyperkeratotic follicular papules, erythematous-desquamative plaques, palmoplantar keratoderma [ 1 ] . Its classification into five subgroups is based on age at onset, clinical course, morphologic features, and prognosis [ 2 ] . We present a type III pityriasis rubra pilaris. The differential diagnosis includes psoriasis vulgaris, perifollicular keratosis, lichen spinulosus.
Figure 1 .
(A,B,E,F) Extensive erythematous scaly eruption on the trunk and limbs. (C,D) Well-circumscribed, red-orange, waxy plaques on the patient palms and soles. (G) Basket-like hyperkeratosis, diffuse orthokeratosis and spotted parakeratosis, and a dermal superficial perivascular lymphocytic infiltration (H&E ×400).