Colloid Adenocarcinoma of the Lung With Concomitant Pulmonary Actinomycosis: A Case Report

Colloid adenocarcinoma of the lung is a rare subtype of lung adenocarcinoma characterised by the destruction of pre-existing airspaces caused by mucin produced by the tumour. Pulmonary actinomycosis is a chronic suppurative lung disease caused by <i>Actinomyces</i> that is sometimes difficult to differentiate from lung cancer. Here, we report a case of pulmonary colloid adenocarcinoma complicated by pulmonary actinomycosis. A 66-year-old male presented with complaints of cough and bloody sputum and was diagnosed with right upper lobe lung adenocarcinoma. During the preoperative waiting period, the lesion rapidly enlarged, prompting an early right upper lobectomy. Histopathological examination confirmed the coexistence of colloidal adenocarcinoma and pulmonary actinomycosis. The coexistence of lung cancer and pulmonary actinomycosis is extremely rare. This case represents an extremely rare coexistence of lung cancer and pulmonary actinomycosis, where a rapidly enlarging lesion was diagnosed through surgical resection.