B73-04 Pulmonary Actinomycosis: A 10-year Experience From a Tertiary Referral Center

Abstract Pulmonary actinomycosis is a rare, chronic, and often misdiagnosed infection that canmimic tuberculosis or malignancy, leading to delayed diagnosis and unnecessary invasiveprocedures. We report a series of histopathologically confirmed cases of pulmonaryactinomycosis diagnosed at a tertiary referral center over a ten-year period, highlightingclinical, radiologic, and therapeutic aspects.A total of 11 cases were included after exclusion of non-granulomatous samples andincomplete data. The mean age at diagnosis was 41.2 years, with a slight femalepredominance (6 women, 5 men). None of the patients were immunosuppressed or hadrelevant non-pulmonary comorbidities. Two patients had a previous history of treatedtuberculosis, and three had an antecedent diagnosis of asthma, of which two were laterconsidered doubtful. The median time from symptom onset to diagnosis was 22 months,reflecting the indolent and misleading presentation of the disease.The most frequent tomographic findings were areas of pulmonary consolidation (6 cases),bronchiectasis (5), mediastinal lymphadenopathy (3), and cavitation (1). The predominantinitial diagnostic hypothesis was pulmonary tuberculosis (8 cases), followed by lung mass(1), abscess (1), and infected bronchiectasis (1). All patients underwent lung biopsy fordefinitive diagnosis, and sulfur granules were identified histologically in a single case.Treatment consisted mainly of prolonged antibiotic therapy with amoxicillin for an averageof 12 months. Eight patients also required surgical intervention, mostly due to hemoptysisor poor response to medical therapy. Clinical outcomes included complete cure in 4patients, partial improvement in 3, and disease stability in 4, with no recorded deaths orrelapses during follow-up.This series represents one of the few histopathologically confirmed cohorts of pulmonaryactinomycosis from a Latin American tertiary center. Despite its benign infectious nature,the disease often simulates more severe conditions such as tuberculosis or cancer, resultingin diagnostic delay. Awareness of its radiologic spectrum and inclusion in the differentialdiagnosis of chronic pulmonary consolidations may prevent unnecessary surgicalresections. Combined medical and surgical management yields favorable outcomes whendiagnosis is established. This abstract is funded by: None