Pityriasis lichenoides: a clinical and pathological case series of 49 patients with an emphasis on follow-up.

The classification of pityriasis lichenoides (PL) into pityriasis lichenoides et varioliformis acuta (PLEVA), PL chronica (PLC) and febrile ulceronecrotic Mucha-Habermann disease (FUMHD) is based on both clinical and chronological features. In this retrospective monocentric study, we aimed to investigate the relevance of the classification in routine practice. We enrolled 49 patients (25 female, 24 male; median age 41 years). The lesions were papular in 76% of patients, necrotic in 12% and mixed in 12%. We found three histological patterns: 'classic' (65%), 'lymphomatoid' (13%) and 'mild' (22%). The 'lymphomatoid' pattern was associated with necrotic presentation and the 'mild' pattern with papular lesions (P = 0.01). Among the 27 patients with follow-up, 18% had relapses and 44% had chronic disease. One patient had mycosis fungoides. Neither clinical nor histological findings were correlated with disease progression, and are a reflection of the intensity of epidermal injury rather than of the disease course. The term 'pityriasis lichenoides' should be preferred to the classic PLEVA/PLC/FUMHD classification.