Mycobacterium haemophilum Masquerading as Leprosy in a Renal Transplant Patient

Opportunistic infections following immunosuppression in solid organ transplant (SOT) patients are common complications with the skin being a common sight of infection. Nontuberculous mycobacteria (NTM) are rare but potential causes of skin infection in SOT patients. We present a case of an adult male immunosuppressed following renal transplantation who presented with an asymptomatic rash for several months. The patient’s skin eruption consisted of erythematous papules and plaques coalescing into an annular formation. After failure of the initial empiric therapy, a punch biopsy was performed that demonstrated nerve involvement suspicious for Mycobacterium leprae. However, culture of the biopsy specimen grew acid-fast bacilli that were subsequently identified as M. haemophilum. His rash improved after a prolonged course of clarithromycin and ciprofloxacin. Both organisms are potential causes of opportunistic skin infections and can be difficult to distinguish with similar predilection for skin and other biochemical and genetic similarities. Ultimately they can be distinguished with culture as M. haemophilum will grow in culture and M. leprae will not. This case was unique due to nerve involvement on biopsy which is classically seen on biopsies of leprosy. 1. Introduction Effective immunosuppression has allowed for the development of many life-saving treatments such as organ transplantation, but it has also opened a Pandora’s Box of potential side effects including opportunistic infections. A wide variety of unique and often diagnostically challenging infections are the frequent result of the immunosuppression needed following solid organ transplant (SOT). Though opportunistic infections with nontuberculous mycobacteria (NTM) are uncommon in SOT patients, when they do occur, the skin and soft tissue are frequent sites of infection. The incidence for NTM infection in renal transplant patients is estimated at 0.16–0.38% with skin and soft tissue being the most common sites of infection [1]. The following case will present a rash initially thought to be leprosy but subsequently diagnosed as dermatitis due to Mycobacterium haemophilum. 2. Case Presentation A 67-year-old male with a history significant for immunosuppression secondary to renal transplantation presented with a 4-month history of an asymptomatic rash and swelling over his right thigh. The eruption developed gradually over several weeks; treatment with an antifungal cream was unsuccessful and a topical corticosteroid cream worsened the eruption. The patient wore a prosthetic limb on his right leg