Hot tub lung: presenting features and clinical course of 21 patients.

BACKGROUND: Hot tub lung is an emerging lung disorder associated with exposure to Mycobacterium avium complex organisms contaminating hot tub water.
OBJECTIVES: To define the clinical characteristics and outcome of patients with hot tub lung.
METHODS: Retrospective review of 21 patients diagnosed with hot tub lung at a tertiary medical center over a 7-year period.
RESULTS: The mean (+/-sd) age at presentation was 46 (+/- 15) years; 9 patients were men (43%). All patients described ongoing exposure to hot tubs. The most common referral diagnoses were sarcoidosis, bronchitis, and asthma. Dyspnea and cough were present in all patients, hypoxemia was noted in 10 patients (48%). High-resolution computed tomography of the chest had been performed in 20 patients and demonstrated diffuse centrilobular nodules and/or ground-glass opacities in all patients. M. avium complex was isolated from the hot tub water, respiratory secretions and/or lung tissue in all patients. Bronchoscopic or surgical lung biopsy was obtained in 18 patients and demonstrated bronchiolocentric granulomatous inflammation. With avoidance of exposure, clinical and radiologic improvement was observed in all patients. Additionally, 13 patients (62%) received corticosteroid therapy, 1 (5%) antimycobacterial therapy, 2 (10%) received both, and 5 patients (24%) received no pharmacologic therapy.
CONCLUSIONS: Hot tub lung likely represents hypersensitivity pneumonitis due to inhalational exposure to M. avium complex. Antimycobacterial therapy does not appear to be required in the management of this disease. Although corticosteroids may be helpful in the treatment of severely affected patients, others can be managed by avoidance of additional exposure alone.