Leprosy-like reaction occurred during the treatment of a cutaneous Mycobacterium haemophilum infection: A case report

Rationale: Mycobacterium haemophilum is a rare pathogen, belongs to the slowly-growing nontuberculous mycobacterium family, and shares a close evolutionary relationship with Mycobacterium leprae . It is a fastidious organism that requires special media(iron or hemin supplementation)and conditions (incubation at 30–32°C) for growth, which differs from most other pathogenic mycobacteria. Patient concerns: A 43-year-old Asian male presented to our outpatient department due to the appearance of multiple infiltrative erythematous nodules and ulcerations on the extremities for more than 2 months. Diagnoses: Acid-fast bacteria were detected in the specimen and sequencing for hsp65 and 16S rRNA genes of the pathogen extracted from the biopsy tissue identified as M haemophilum . The diagnosis of cutaneous M haemophilum infection was established. Interventions: The patient received a 3-drug regimen (oral clarithromycin 1.0 g/d, rifampicin 0.6 g/d, and moxifloxacin 1.0 g/d) and local hot compression therapy, the dose of immunosuppressant was reduced. Outcomes: The lesions gradually improved after 6 months of continuous antibiotic therapy. There is no recurrence of erythema papules and nodules. Lessons: This case shows that the patient’s condition may be exacerbated immediately after the initiation of anti-nontuberculous mycobacterium therapy, which is analogous to the leprosy reaction. A high degree of clinical suspicion for the underlying disease is critical to avoid unnecessary interruption of treatment.