Atypical presentations of erythema nodosum leprosum: Diagnostic and therapeutic aspects

Classic erythema nodosum leprosum (ENL) is characterized clinically by abrupt eruption of tender erythematous nodules, papules and plaques. Variable atypical patterns have been described, for example pustular, bullous, ulcerative, necrotic and Sweet's syndrome-like ENL. We aim to review previously reported cases of atypical ENL addressing the diagnostic and therapeutic aspects of these uncommon presentations. A search of medical literature for all cases of atypical ENL was conducted in the PubMed database till 2020. Data of patients with atypical ENL were collected and analyzed to describe the epidemiological, clinico-histological and therapeutic features. The major five clinically described presentations of atypical ENL include vesiculo-bullous lesions (46 % of patients), ulcero-necrotic lesions (41 %), erythema multiforme-like lesions (28 %), Sweet's syndrome-like lesions (11 %) and pustules (9 %). The skin lesions were accompanied by fever and constitutional symptoms in all patients. Oral steroids and thalidomide were the main lines of therapy in most of the reported patients. Dermatologists and pathologists should keep in mind the clinical variability of ENL to avoid misdiagnosis and delayed management. Early recognition can help control disease progression and save the patients from further complications.