A unique case of hot tub lung worsening during the winter

Summer-type hypersensitivity pneumonitis includes a spectrum of granulomatous lung diseases that result from the inhalation of Trichosporon species in the summer. Hot tub lung is a granulomatous lung disease caused by the inhalation of water aerosols containing non-tuberculous mycobacteria. We herein describe a case of hot tub lung that deteriorated during the winter season. Every winter, the patient's symptoms, laboratory findings and chest images worsened. Genetically identical Mycobacterium avium strains were detected in his sputum and bathtub. The circulation of bathtub water during the winter months only exacerbated his symptoms in the winter.