Mycobacterium fortuitum is a rapidly growing mycobacterium found in soil and water throughout the world. It can cause diseases in immunocompetent patients, usually resulting in localized skin and soft tissue infections. Cervical lymphadenitis caused by M. fortuitum is rare. We report a 46-year-old woman in whom skin lesions of cutaneous polyarteritis nodosa, leucocytoclastic vasculitis and Sweet's syndrome had successively developed before the diagnosis of cervical lymphadenitis caused by M. fortuitum was made. The skin lesions responded to colchicine and systemic corticosteroids but recurred intermittently. After establishment of the diagnosis, she received treatment with clarithromycin and ciprofloxacin. The cervical lymph nodes decreased in size 6 months later and no more new skin lesions were found.