Endobronchial Actinomycosis - The Great Masquerader.

Actinomycosis is a rare infection caused by Gram-positive, facultative anaerobic bacteria of the Actinomyceataceae family. Pulmonary Actinomycosis has a strong clinical and radiological resemblance to tuberculosis, lung abscess, and lung cancer, leading to missed or delayed diagnosis. We present a case of an elderly male with a productive cough and weight loss with right upper lobe consolidation on imaging. Definitive diagnosis was by histopathology; drawing samples by fiber-optic bronchoscopy, broncho-alveolar lavage, and endobronchial ultrasound. Tuberculosis, fungal infection, and malignancy were ruled out. Diagnosis was confirmed by demonstration of filamentous colonies of Actinomyces on hematoxylin and eosin and Grocott-Gomori's methanamine silver stain. The patient showed good clinical and radiological response to Penicillin therapy.