Pancoast's syndrome secondary to thoracic actinomycosis.

Pancoast's syndrome is almost exclusively caused by a malignant apical lung tumor invading the structures of the thoracic outlet. We report a case of thoracic actinomycosis as a cause of Pancoast's syndrome. A 65 y/o bm presented with a 6 month history of nonproductive cough, weight loss, a left upper lobe infiltrate, and a positive PPD of 20 mm. He failed to improve with triple antituberculous therapy for 3 months with worsening of left upper lobe disease. CT scan of the chest showed a mass lesion of the left upper lobe. Bronchoscopy with BAL and biopsy as well as percutaneous fine needle aspiration failed to reveal a diagnosis. Patient developed Pancoast's syndrome characterized by reflex sympathetic dystrophy with pain, swelling, and numbness of left shoulder, arm, and hand. A thoracoscopic left upper lung biopsy was performed and histologic examination revealed sulfur granules containing filamentous organisms characteristic of Actinomyces species. All sections were negative for malignancy. AFB stain and culture were negative. Patient was clinically cured following a 6-month course of penicillin with resolution of the left upper lobe mass. Although rare, thoracic actinomycosis must be considered in the differential diagnosis of Pancoast's syndrome. This case emphasizes the importance of obtaining a precise etiologic diagnosis before a treatment decision is made.