ABSTRACT
A 75 year old woman was admitted for evaluation of right lung mass. She was not a smoker. She had been diagnosed as uterine prolapse and during preoperative assessment a lung mass was found incidentally on simple chest X-ray. On chest CT scan, 3.5x2 cm sized homogeneous mass was located in the anterior segment of right upper lobe and there were multiple calcified lymph nodes in both hilum and mediastinal area. We performed diagnostic bronchoscopy, but no definite endobronchial mass was found. Next we did CT guided percutaneous fine needle aspiration biopsy. On microscopy, sulfur granules consisting of multiple granular basophilic centers with hyaline projection of branching filaments were noted. From this finding we made a diagnosis of pulmonary actinomycosis.