Multiple hyalinizing granulomas mimicking pulmonary malignancy

Pulmonal hyalinizing granuloma (PHG) is a rare benign disease of unknown cause, first described by Engleman in 1977 (1). Fewer than 200 cases have been reported worldwide (2). We present the case of a middle-aged male referred to the respiratory clinic after a routine chest X-ray (CXR) and chest computed topography (CT) scan revealed multiple bilateral peripheral pulmonary lesions (PPL). Over a 10-year period, the patient´s PPLs increased in size and number, with heterogeneous hypermetabolism observed on fluorodeoxyglucose -positron emission tomography (FDG-PET) imaging. Initially, the PPLs were suspected to be metastases from a salivary gland cancer due to a hypermetabolic focus in the right parotid gland. However, a biopsy of the parotid gland revealed a benign Warthin's tumour, and CT-guided fine needle biopsies from the lung lesions did not show malignant cells. A thoracoscopic resection of one PPL was consistent with a diagnosis of hyalinizing granuloma.