The article describes a case of hot tub lung initially treated as nonfibrotic hypersensitivity pneumonitis and discusses its possible immune-mediated and infectious mechanisms.
Approach:
Case: A 66-year-old woman had progressive respiratory symptoms and persistent imaging abnormalities despite more than two years of treatment for presumed nonfibrotic hypersensitivity pneumonitis.
Evaluation: Further history identified daily indoor hot tub use beginning before symptom onset. Imaging and lung biopsy showed findings consistent with hot tub lung; rare MAC organisms were seen on staining, but bronchoalveolar lavage culture was negative.
Management: Hot tub use was stopped, immunosuppression was tapered, and azithromycin, ethambutol, and rifabutin were started.
Key Findings:
The patient’s respiratory symptoms markedly improved after hot tub cessation and initiation of antimycobacterial therapy.
Serial imaging showed complete radiologic resolution approximately 24 months after presentation.
The authors considered the findings most consistent with hot tub lung due to hypersensitivity pneumonitis in the setting of MAC exposure, with a possible infectious component.
Interpretation:
The authors describe hot tub lung as potentially involving both immune-mediated and infectious mechanisms. They note that exposure avoidance may be sufficient in many reported cases, while antimycobacterial treatment is generally reserved for selected patients with evidence suggesting MAC infection or failure to improve with other measures.
Limitations:
Hot tub water and filter components were not cultured, so the hot tub could not be definitively confirmed as the MAC source.
Bronchoalveolar lavage culture was negative, and definitive evidence of active infection remained limited.
Conclusion:
The authors state that persistent or treatment-refractory interstitial lung disease may warrant reassessment of the presumed antigen source and disease mechanism, including targeted questions about hot tub exposure.
