RELAPSE OR REACTION: POST-MDT ERYTHEMA NODOSUM LEPROSUM AS AN INITIAL DIAGNOSTIC DILEMMA IN PRIMARY CARE

Abstract

Leprosy is a chronic infectious disease caused by Mycobacterium leprae that remains a health problem in endemic countries such as Indonesia. The challenge lies not only in early diagnosis but also in the identification of post-treatment immunological complications. Although multidrug therapy (MDT) is effective in reducing case numbers and preventing disability, leprosy reactions may still occur and give rise to diagnostic difficulties. Type 2 leprosy reaction, or Erythema Nodosum Leprosum (ENL) is a complex immune response that may mimic leprosy relapse or recurrence, defined as the reappearance of signs and symptoms of leprosy after the patient has adequately completed Multidrug Therapy (MDT), particularly when accompanied by new skin lesions, systemic symptoms, and persistently positive bacteriological findings.
We report a 30-year-old man with a history of multibacillary (MB) leprosy who had completed MDT and, eight months after therapy, presented with fever, new skin lesions, and extremity edema. The slit skin smear showed an increase in the bacteriological index (BI) from +1 to +2, which initially raised suspicion of relapse; however, further evaluation established the diagnosis of ENL. This case highlights that the presence of bacilli and new lesions after MDT does not always reflect recurrence, but may instead represent a manifestation of an immunological reaction; hence, the ability to distinguish relapse from ENL in primary care is crucial to prevent misdiagnosis and to ensure appropriate management.