Primary pulmonary actinomycosis: a retrospective analysis of 145 cases in mainland China.

OBJECTIVE: To improve our understanding of pulmonary actinomycosis.

METHODS: A retrospective analysis of 145 cases in mainland China was conducted.

RESULTS: The male:female ratio was 2.7:1. Mean age at diagnosis was 48 years (± 12). Main symptoms were cough (87.6%), expectoration (40%), blood-stained sputum (37.2%), fever (26.9%), chest pain (24.8%) and haemoptysis (16.6%). Eighty-eight (60.7%) patients had no underlying disease. Only five patients received a correct initial diagnosis; 60 patients were misdiagnosed with lung cancer, followed by pulmonary tuberculosis (TB) and lung abscess. Most patients were diagnosed using surgical resection, transthoracic needle aspiration or flexible bronchoscopy. Sixty-seven patients received penicillin G, and one patient did not receive any antibiotics after surgery. The mean duration of treatment with antibiotics was 4.5 months (±3.7). Overall, 110 (75.9%) patients were fully cured, 4 died, 1 was lost to follow-up, and a record of the prognosis was not available for 30 patients. Mean duration of follow-up was 26 months (± 32).

CONCLUSION: Pulmonary actinomycosis is a rare bacterial infection and is often misdiagnosed as lung cancer or pulmonary TB. The definitive diagnosis depends on pathology; sulfur granules are suggestive, but not specific. Penicillin G is the standard treatment. The optimal duration of antibiotic treatment merits further investigation.