Actinomyces are gram-positive anaerobic bacteria often present in the normal flora of the oropharynx and gastrointestinal tract. Thoracic actinomycosis most commonly occurs from oropharyngeal aspiration, although it can occur hematogenously or by direct extension from adjacent infected tissues. Thoracic infection usually involves lung parenchyma, pleura, mediastinum and chest wall (12). Primary endobronchial actinomycosis has rarely been reported.
A 43 year old woman was admitted with an 18 month history of cough, blood-tinged sputum and a persistent right middle lobe infiltrate despite multiple courses of antibiotic therapy. 2 prior bronchoscopies showed an endobronchial lesion obstructing the bronchus intermedius, but biopsies showed only granulation tissue and chronic inflammation. On physical examination she was an afebrile, edentulous patient, with focal wheezing in the right lower lung field. Her ESR was 30mm/hr and complete blood count and differential were normal. HIV and PPD tests were negative. Chest x-ray demonstrated an infiltrate in the right middle lobe. A flexible bronchoscopy revealed an endobronchial lesion causing a near-total occlusion of the bronchus intermedius with a distal white, hard fungating mass (Figure 1). Histologic examination of the mass showed edematous and chronically inflamed bronchial mucosa with gram-positive filamentous bacterial clusters consistent with actinomyces (Figure 2). Cytology from the BAL showed sulfur granules (Figure 3). In addition, culures from the BAL yielded pseudomonas aeruginosa. A rigid bronchoscopy was performed and a foreign body (eraser tip) was removed from the bronchus intermedius. Therapy with piperacillin-tazobactam to cover both actinomyces and pseudomonal infections was given for a total of 14 days and then switched to ampicillin-clavulinic acid for a total of 6 months of therapy.DISCUSSION: Thoracic actinomycosis, accounting for 15% of all cases, usually presents as a slow, indolent mass or pneumonitis. Cavitation, hilar adenopathy and pleural involvement may be present. Extension across fissures, into mediastinum and to the chest wall with soft tissue masses can mimic malignant diseases (1). Endobronchial actinomycosis associated with a foreign body aspiration is rare. In the last 30 years a few cases have been reported (345). As seen in our case, bronchoscopies can be misleading but with appropriate biopsy sampling, handling of specimens and combining both microbiologic and pathologic findings the chances for an accurate diagnosis are enhanced. Actinomyces is a facultative organism, but optimal growth requires strict anaerobic processing and when suspected the microbiology laboratorist should be alerted. Actinomycosis develops when there has been disruption of the mucosal barrier such as it can occur with the aspiration of the foreign body. In all prior reports, succesful treatment required removal of the foreign body via rigid bronchoscopy and antibiotics. Duration of therapy should be extended beyond resolution of clinical disease to prevent relapses.
Thoracic actinomycosis can present as an endobronchial lesion mimicking malignant disease. Its presence should alert the physician to proceed with more invasive testing to rule out foreign body aspiration.
A.R. Abreu, None.