Dermoscopy may be a valuable additional tool in diagnosis of pityriasis rubra pilaris: Letter to the editor

Abstract

Eighteen-year-old female patient with with red scaly plaques on her forearms, legs and scalp, was referred to our out-patient clinic (Figure 1). The disease duration was over 10 years. The female patient was previously diagnosed as psoriasis. She was treated with various topical anti-psoriatic agents unsuccessfully. The lesions were not completely cleared. The patient was evaluated and clinical differential diagnosis included a number of erythematosquamous skin diseases. Due to the shape and arrangement of lesions , the diagnosis of seborrheic dermatitis, pityriasis rosea, lichen planus, pityriasis lichenoides et varioliformis acuta, pityriasis lichenoides chronica and parapsoriasis were excluded. And preliminary diagnosis of pityriasis rubra pilaris (PRP) and psoriasis were concluded. Skin punch biopsy was performed from her left forearm. Histopathological examination showed parakeratosis, loss of granular layer limited to small foci with diffuse hypergranulosis, and perivascular lymphocyte, histiocytes and extravasated erythrocytes in upper dermis (Haematoxylin-Eosin, original magnification x100) (Figure 2). These histopathological features were not fully consistent with psoriasis and did not exclude the diagnosis of PRP. Later, we performed dermoscopic examination on erythematous plaques and it revealed round/ oval yellowish areas surrounded by vessels of mixed linear and dotted morphology