[Chronic paronychia and synovialitis of extensor tendons due to Mycobacterium marinum. Is diagnosis or treatment the problem?].

Most infections of the upper extremity are caused by staphylococcus or streptococcus and respond well to beta-lactam antibiotics. Hand surgeons should be aware of the possible diagnosis of Mycobacterium marinum infection: 90% of the lesions are found in the upper extremity. We present a case of a chronic, cutaneous lesion of the right middle finger with synovialitis of the extensor tendons observed in a 35-year-old woman. Routine cultures from tissue of the infected finger led to the diagnosis of paronychia due to staphylococcus aureus. Despite surgical and antibacterial treatment, the lesion persisted and the patient developed multiple raised, non-tender satellite lesions to the right hand and elbow. Based on the clinical aspect and a detailed history (she kept fish and had suffered a chicken bone stab to her middle finger 12 weeks earlier), we suspected a Mycobacterium marinum infection. Tissue was obtained mainly by synovialectomy. Culture of the biopsy tissue for Mycobacterium marinum confirmed the diagnosis. The patient responded to a triple therapy (rifabutin, ethambutol and clarithromycin) and had an uncomplicated recovery. The importance of a high index of suspicion, adequate examination and a complete patient's history for a correct diagnosis is stressed. Culture for Mycobacterium marinum is not routinely performed and ought to be initiated once an infection is suspected. We also discuss the best timing for the onset of medical treatment.