False-positive PET-CT scan secondary to interstitial pneumonitis mimicking malignancy in fire eater's lung

Abstract

Inhalation of flammable oily hydrocarbons may cause interstitial pneumonitis by diffusion throughout the bronchial mucosa and alveoli.

A 70 year old male was admitted with progressive dyspnoea, fever, haemoptysis, cough, and sputum for 6 weeks. Physical examination revealed fine crackles on the right side of thorax, and O2 sat: 94%. He had performed fire-eating show 6 weeks ago. Chest x-ray showed irregular opacity on the right lower zone. Thorax computed tomography (CT) was reported a mass (12x11mm) located in the medial and right lower lobe, surrounded the middle lobe bronchus and pulmonary vein, invades to the hilar area, and diaphragm, and surrounded with multiple nodules. Parenteral antibiotic was given since he had leucocytosis, elevated procalsitonin, and sedimentation (111/hr). After 4 weeks, positron emission tomography (PET)-CT was resulted as right hilar lymphadenopathy (19x22mm, SUV: 5), and mass (53x77mm, SUV: 8.7) with satellite nodules and ground glass opacity. Diagnostic bronchoscopy revealed erythema and narrowing of the entrance of medial lobe. Bronchial lavage (BL), and bronchial mucosa biopsy was negative for any pathogens, and malignancy. Transthoracic needle lung biopsy was consistent with “interstitial pneumonitis”. Oral corticosteroid was started as 1mg/kg/day, and gradually tapered in 3 months. Finally, his clinical findings were improved, as well as radiologic abnormalities.

This case illustrates the importance of considering interstitial pneumonitis in fire eaters even some findings are incompliant such as false-posivitiy in PET-CT, and no demonstration of lipid laden macrophages in BL.