Hidden Imitator

Abstract Pulmonary actinomycosis presents a diagnostic challenge due to its clinical and radiological resemblance to malignancy, tuberculosis, and chronic pneumonia. The endobronchial subtype is exceptionally rare and frequently misinterpreted as a neoplastic process. Although foreign body aspiration has been proposed as a predisposing factor for primary endobronchial actinomycosis, documented cases remain limited. This report describes 2 cases of endobronchial actinomycosis associated with presumed organic foreign body aspiration. The first case involved a 72-year-old woman with chronic dyspnea and chest pain. Imaging and bronchoscopy revealed an obstructive lesion in the bronchus intermedius with features suggestive of a calcified or ossified structure. Histopathological analysis confirmed pulmonary actinomycosis, and the patient improved following bronchoscopic removal and antibiotic therapy. The second case describes a 62-year-old man with chronic obstructive pulmonary disease and persistent dyspnea. Computed tomography revealed an endobronchial lesion in the left lower lobe. Bronchoscopy showed granulomatous inflammation containing bone-like fragments, and histological evaluation confirmed Actinomyces infection. The patient responded well to antibiotic treatment. In both cases, the foreign bodies were surrounded by marked granulomatous reaction, which precluded identification of their precise composition or origin. Primary endobronchial actinomycosis secondary to organic foreign body aspiration is exceedingly rare. Its clinical and radiological resemblance to malignant and infectious diseases underscores the importance of bronchoscopy and histopathological evaluation for accurate diagnosis and appropriate therapeutic management.