Pulmonary granulomas and Mendelson syndrome in an immunocompromised patient

Granuloma formation is generally correlated with infection. Pulmonary granulomas caused by foreign bodies aspiration are uncommon. The clinical and radiologic features of such cases often lack specificity, which makes it difficult to distinguish from malignancy. Aspiration is usually not considered in the differential diagnosis of patients presenting with mass-like abnormalities on chest imaging. Occult aspiration history, diverse clinical manifestations, atypical imaging findings, and limited availability of pathogen detection techniques make the precise diagnosis a substantial challenge. Herein, we describe an older patient presenting with chest pain and worrisome lung masses/nodules that proved to be pulmonary granulomas caused by foreign matters aspiration. In addition, the patient developed Mendelson syndrome due to acute macroaspiration. Lung tissue metagenomics next-generation sequencing (mNGS) revealed Streptococcus intermedius, a normal flora of the oropharynx. The aim of this case was to underscore the importance of considering aspiration as a potential differential diagnosis of patients presenting with pulmonary granulomas, especially in patients with recurrent pneumonia or predisposing factors. In addition, mNGS act as a potential, rapid, and effective technique for diagnosing aspiration-related syndrome, showing satisfactory performance in identifying pathogens.