Background: Endobronchial actinomycosis is a rare form of pulmonary actinomycosis most often associated with foreign body aspiration. We report a case of endobronchial actinomycosis without a foreign body aspiration diagnosed with bronchial biopsy.
Case Report: A 65-year-old man presented with fever, cough, and occasional hemoptysis. A chest radiograph showed right paracardiac opacity. There was no response to 14-day antibiotherapy; therefore, thoracic computerized tomography was planned. Computerized tomography scanning revealed a mass lesion and reticulonodular infiltration of the lateral segment of the right middle lobe. A fiberoptic bronchoscopy was performed because lung cancer was suspected; vegetations narrowing the lumen, covered partially by purulent exudate, were observed in the lateral segment of the right middle lobe. Actinomyces granules were seen on histopathologic examination of the bronchoscopic biopsy specimen. A diagnosis of endobronchial actinomycosis was made and ampicillin was administered for 6 weeks. A clinical and radiologic response was achieved at the end of treatment, and no recurrence has been observed in 10 months of follow-up.
Conclusions: Diagnosis of endobronchial actinomycosis by bronchoscopic biopsy will prevent the patient from invasive procedures, even surgery. Pulmonary actinomycosis may mimick lung cancer, and must be considered in the differential diagnosis of endobronchial lesions and persistent densities on chest radiographs.

Keywords: Actinomycosis, endobronchial, lung cancer