Role of azathioprine in preventing recurrences in a patient of recurrent erythema nodosum leprosum

The pathogenesis of erythema nodosum leprosum (ENL) involves both immune complex deposition and dysfunction of cell mediated immunity. Tumour necrosis factor-alpha (TNF-alpha) plays an important role in its pathogenesis. Thalidomide and corticosteroids are the mainstay of treatment for ENL. However, there are often severe limitations to their use. We report a case of recurrent ENL treated successfully with azathioprine. A 15-year-old unmarried girl with lepromatous leprosy had recurrent ENL for 2 years. She was treated with WHO-MB MDT and prednisolone in doses of 40-90 mg a day for 2-12 weeks. Her condition was inadequately controlled. The patient was therefore treated with thalidomide 300 mg and prednisolone 40 mg. The symptoms subsided after 5 days and ENL lesions healed in 2 weeks. Prednisolone was reduced by 10 mg per week and stopped, while thalidomide was reduced to 100 twice daily after 4 weeks. Azathioprine 100 mg (2 mg/kg per day) daily orally was added to prevent recurrences. Thalidomide was further reduced and stopped after another 4 weeks while she continued with azathioprine in the same doses for 8 months. There was no recurrence of ENL lesions and no side effects of the therapy. MB-MDT was stopped 1 year ago, and she is on follow-up without any relapse. Azathioprine, therefore, appears to be an effective and safe drug to prevent recurrences of ENL.