Pulmonary actinomycosis

Pulmonary actinomycosis is a rare, indolent, subacute-to-chronic bacterial infection of the respiratory tract caused by filamentous, anaerobic or microaerophilic, gram-positive bacteria of the genus *Actinomyces*, most commonly *Actinomyces israelii* Pathophysiologically, the disease is characterized by slowly progressive, suppurative granulomatous lung parenchymal necrosis, dense fibrosis, abscess formation, and the potential to transgress anatomical tissue planes, sometimes leading to empyema ...

Pulmonary actinomycosis is a rare, indolent, subacute-to-chronic bacterial infection of the respiratory tract caused by filamentous, anaerobic or microaerophilic, gram-positive bacteria of the genus *Actinomyces*, most commonly *Actinomyces israelii*

It primarily affects adults—frequently individuals with underlying risk factors such as poor oral hygiene, periodontal disease, alcohol use disorder, or chronic pulmonary disease—following the aspiration of commensal oropharyngeal secretions into the lower airways Due to its indolent presentation and invasive mass-like infiltrates, it frequently mimics pulmonary tuberculosis or thoracic malignancy

It primarily affects adults—frequently individuals with underlying risk factors such as poor oral hygiene, periodontal disease, alcohol use disorder, or chronic pulmonary disease—following the aspiration of commensal oropharyngeal secretions into the lower airways

Pathophysiologically, the disease is characterized by slowly progressive, suppurative granulomatous lung parenchymal necrosis, dense fibrosis, abscess formation, and the potential to transgress anatomical tissue planes, sometimes leading to empyema or draining chest wall sinus tracts marked histopathologically by pathognomonic sulfur granules

Due to its indolent presentation and invasive mass-like infiltrates, it frequently mimics pulmonary tuberculosis or thoracic malignancy