A case of panniculitis caused by Mycobacterium massiliense mimicking erythema induratum

Among nontuberculosis mycobacteria (NTM), rapidly growing mycobacteria (RGM) are the most common causative agents of soft tissue infection. Mycobacterium massiliense, a new species of NTM, was isolated in 2004. Due to the lower virulence of RGM, M. massiliense infection is rare in the general population. Here, we report a case of multiple infective panniculitis, due to M. massiliense, mimicking erythema induratum in a patient with Cushing syndrome. The organism was identified using traditional mycobacterial culturing and staining methods as well as molecular approaches, including erythromycin ribosome transferase gene polymerase chain reaction. The patient was treated with clarithromycin for 9 months, based on antibiotic susceptibility testing.