Exogenous Lipoid Pneumonia Induced by the Excessive Use of Menthol-containing Nasal Inhalers and Subsequent Acute Hypersensitivity Pneumonia Triggered by Domestic Environmental Antigens.

A 58-year-old Japanese man presented at our hospital with respiratory failure. Computed tomography (CT) revealed scattered fat-attenuated consolidations, and bronchoalveolar lavage fluid (BALF) showed neutrophilia, leading to a diagnosis of exogenous lipoid pneumonia (ELP) caused by the excessive use of a menthol-containing nasal inhaler. Despite a temporary improvement, the patient experienced recurrent respiratory failure shortly after discharge. CT revealed centrilobular ground-glass opacities, and a bronchoalveolar BALF analysis revealed lymphocytosis, suggesting acute hypersensitivity pneumonitis (AHP) triggered by domestic environmental antigens. Antigen avoidance was successful and remission was maintained. The rare sequential occurrence of AHP following ELP suggests a potential pathophysiological connection between these conditions.