B71-04 Pulmonary Actinomycosis Associated With Broncholithiasis: A Rare Mimicker of Malignancy Diagnosed by Bronchoscopy

Abstract Introduction Broncholithiasis, a rare condition caused by calcified material within the bronchial lumen, can mimic malignancy and predispose to recurrent infections. Pulmonary actinomycosis associated with broncholiths is exceptionally uncommon, with fewer than 20 cases reported. Diagnosis is often delayed due to nonspecific imaging findings. Case Report A 62-year-old woman with hypertension, osteoarthritis, and prior tobacco use was evaluated for an abnormal chest CT showing a calcified endobronchial lesion in the left upper lobe bronchus with post-obstructive mass-like consolidation. Flexible bronchoscopy revealed obstruction of the left upper lobe and lingula segments due to a lodged broncholith. The lesion was removed using biopsy forceps and cryotherapy, exposing granulation tissue and necrotic debris. Histopathology demonstrated filamentous organisms with sulfur granules consistent with Actinomyces species; stains for acid-fast bacilli and malignancy were negative. The patient received prolonged intravenous penicillin therapy, with complete radiologic resolution on follow-up imaging. Discussion Pulmonary actinomycosis is a chronic infection that can radiographically resemble tuberculosis or malignancy. In this patient, the broncholith served as a nidus for secondary infection. Bronchoscopic removal provided both diagnostic tissue and therapeutic relief. This case emphasizes the importance of histopathologic evaluation in necrotizing or obstructive lung lesions and underscores that rare post-obstructive infections should be considered when common etiologies are excluded. Conclusion Broncholithiasis can serve as a nidus for pulmonary actinomycosis, a rare but treatable cause of endobronchial obstruction. Clinicians should maintain a high index of suspicion for actinomycosis in post-obstructive infections when malignancy and tuberculosis are ruled out. Bronchoscopy remains a diagnostic and therapeutic cornerstone. Impact Statement This case demonstrates a rare but clinically significant association between broncholithiasis and pulmonary actinomycosis, which can mimic malignancy and delay diagnosis. Early recognition and bronchoscopic intervention are critical to improve outcomes and avoid unnecessary surgery. Learning Objectives 1. Recognize the clinical and radiographic features of broncholithiasis and its complications. 2. Understand the diagnostic challenges and role of histopathology in pulmonary actinomycosis. 3. Appreciate the therapeutic importance of bronchoscopy in endobronchial obstruction from rare infections. This abstract is funded by: None