Bullous Erythema Nodosum Leprosum: a rare case
Introduction: Leprosy is a chronic granulomatous infection caused by Mycobacterium Leprae. There are two types of Lepra reaction, Reversal Reaction (type 1 lepra reaction) and Erythema nodosum leprosum (type 2 lepra reaction). Skin lesions in type 2 lepra reaction manifest as numerous erythematous and tender nodules and plaques in different parts of the body. Bullous lesions are rarely found in type 2 lepra reaction.
Case Report: A 31 years old male, with multiple painful reddish swelling and fluid filled lesions in his face, trunk and extremities. He has been diagnosed as lepromatous leprosy on WHO multidrug therapy (MDT) for the past 13 months. There were several history of type 2 lepra reaction, which manifest as multiple painful reddish swelling without any fluid filled lesions before. They were usually managed by high doses of corticosteroids result in improvement. For the first time, on this occasion he had also developed multiple fluid filled lesions. Dermatological examinations revealed multiple erythematous tender nodules and plaques on face, trunk and extremities. He also had multiple bullous lesions on upper and lower extremities. Nikolsky sign was negative. Bilateral ulnar nerves were thickened and tender. Laboratory results revealed anemia, polymorphonuclear leukocytosis and increased ESR. Slit skin smear examination showed solid and fragmented acid fast bacilli with bacteriological index (BI) of 2 2/3 + and morphological index (MI) of 8%. Skin biopsy of bullous lesion show subcorneal bullae with diffuse polymorphonuclear cell infiltrate in the dermis, a few foamy histiocytes, vasculitis, and neutrophilic panniculitis. He was treated with a high dose systemic corticosteroid, intravenous injection of methylprednisolone starting at 62,5mg/day and tappered off over one month period. Anti leprosy drugs were continued. Topical treatments consist of normal saline wound dressing and application of topical antibiotic. He showed good response to the treatment. Discussion Lepra reactions caused by an alteration of immunological balance in a leprosy patient. Erythema nodosum leprosum is an immune complex reaction and seen mostly in lepromatous type. Antibodies reacts to M.leprae antigen to form the immune complex which circulated and deposited in various tissues. This process will lead to activation of complement and causing damage of the tissues. Bullous lesions in type 2 reactions are very rare. There were only a few reports of bullous erythema nodosum leprosum. They have been associated with very high bacillary load in lepromatous leprosy patients.