Cutaneous infection due to Mycobacterium szulgai in a patient with myelodysplastic syndrome

Abstract

Dear Editor, Mycobacterium szulgai is an uncommon non-tuberculous mycobacterium (NTM). Pulmonary disease is the most common clinical presentation of infection with M. szulgai, but few skin infections have been described. Here, we report a case of cutaneous infection and mediastinal lymphadenopathy due to M. szulgai in a patient with myelodysplastic syndrome (MDS).A 59-year-old Japanese man presented to our hospital with a 2-week history of multiple asymptotic skin lesions. He had been diagnosed with MDS 2 years prior and had been treated with prednisolone 27.5 mg and cyclosporin 100 mg daily. On examination, there were uniform 2-3-cm, flesh-colored nodules on his left chest (Fig. 1a) and erythematous infiltrated plaque on his left posterior thigh (Fig. 1b). Computed tomography (CT) showed multiple enlargement of the right mediastinal lymph nodes. Histological examination of cutaneous lesions of the left chest demonstrated granulomatous inflammation that ranged from the dermis to middle layer of fat tissue (Fig. 1c). There was a marked, focal neutrophilic infiltrate and central necrosis, which were surrounded by epithelioid histiocytes. Multinucleated giant cells were also observed. Culture of the biopsy specimen grew acid-fast bacilli, which were identified as M. szulgai subsequently by the DNA-DNA hybridization method. 1 Susceptibilities of the isolates were not available. The patient was commenced on a daily regimen of levofloxacin 500 mg, azithromycin 500 mg and ethambutol 1000 mg. The skin lesions showed immediate but slow improvement, and complete resolution was achieved following 12 months of antimycobacterial therapy. Eventually, mediastinal lymph nodes decreased in size to normal on CT. There was no evidence of recurrence of skin lesions during a follow up of 12 months.Mycobacterium szulgai was first described in 1972. 2 It is a rare pathogen in humans and the incidence of infections of the species accounts for less than 0.5% of all NTM infections. 3 M. szulgai infections demonstrate a variety of clinical manifestations, but mainly pulmonary disease. Cutaneous infections due to M. szulgai are very rare. A review of the English-language published work revealed only 10 cases of cutaneous infection due to M. szulgai, including six cases of primary skin infections and three cases of disseminated diseases. Seven out of 10 patients had an underlying condition of impaired systemic immunity. In our case, it seems that an immunocompromised condition due to MDS and immunosuppressive therapy predisposed the patient to disseminated disease as with other (a) (c) (b) Figure 1. (a) Reddish infiltrated nodules on left chest. (b) Erythematous infiltrated plaque on left posterior thigh. (c) Histological examination showed granulomatous inflammation with epithelioid histiocytes and neutrophils (hematoxylin-eosin, original magnification 9200).

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