Hot Tub Lung: A Diagnostic Challenge

Abstract

Hot tub lung (HTL) is a granulomatous lung disease thought to occur as a result of a hypersensitivity response to non-tuberculous mycobacteria (NTM). Typical radiographic findings are diffuse micronodular and/or ground glass opacities. We report an interesting case of HTL that presented with unique radiographic features, making its diagnosis a predicament. A 56-year-old immunocompetent female with chronic dyspnea and dry cough was found to have subcentimeter cavitary nodules, predominantly in the upper lung zones. Tissue culture obtained via bronchoscopy was positive for Mycobacterium avium complex (MAC). The patient’s clinical and radiographic status, however, deteriorated on antimycobacterial therapy. Complete clinical and radiographic resolution was achieved only after avoidance of hot tub use and treatment with steroids. We believe this is the first reported case of HTL manifesting as cavitary lung nodules with mediastinal lymphadenopathy, and we recommend physicians keep HTL in consideration when encountering patients with these radiographic findings.

Nodular distribution pattern on chest computed tomography (CT) in patients diagnosed with nontuberculous mycobacteria (NTM) infections

“…Many studies on NTM lung infection spread focus on a local/continuous spread in view of consolidation with or without cavitation [4], bronchogenic spread -centrilobular peribronchial nodules ("tree-in-bud" pattern) [23][24] and haematogenous spread -random nodular pattern [25]. Other studies compare the radiomorphological presentation of TB and NTM lung infections, showing similar patterns, including both consolidation and nodular appearances, but to a lesser extent [26][27][28].…”