Abstract: As a rare atypical mycobacterium, Mycobacterium cosmeticum can cause cutaneous granuloma. We report the first case in China of Mycobacterium cosmeticum infection. A 22-year-old female presented with erythema on the right arm for cat bite for 2 months and the past medical history was healthy. The histopathology was consistent with infectious granuloma and tended to atypical mycobacterium infection. The skin tissue was sequenced and the phylogenetic tree analysis was carried out. The final diagnosis was Mycobacterium cosmeticum infection. After the long-term treatments with adjusted medication, the lesion subsided by using condition by using ciprofloxacin, clarithromycin, and minocycline.

Key words: Mycobacterium cosmeticum, infective granuloma