A 43-year-old man was admitted to our hospital with one-month history of productive cough. He had a 3-year history of mitral stenosis and an operation for mitral valve replacement. There was no history of recurrent infection or other evidence of immunodeficiency. Physical examination revealed a temperature of 36.8 C. Chest examination revealed an inspiratory crackle in the right lower lung field. Laboratory tests revealed a leukocyte count of 11,600/muL and hemoglobin of 13.2 g/dL. Differential cell count disclosed the following values: neutrophils 76%; lymphocytes 17%; monocytes 5%; eosinophils 1.7%; basophils 0.3%. Chest radiograph showed focal consolidation of the right lower lobe (Figure 1). Computed tomography of the chest demonstrated patchy air-space consolidation and atelectasis of the right lower lobe (Figure 2). Gram stain showed many Gram positive cocci; AFB smear and culture for Mycobacterium tuberculosis were negative; there were no fungi. Fiberoptic bronchoscopy showed subtotal occlusion of the right superior segment of the lower lobe by a yellow-white, stony-hard mass, which was surrounded by inflamed and edematous bronchial mucosa (Figure 3). Histologically, the biopsy specimen revealed an inflammatory cellullar infiltration and colonies which were formed of a radiating network of filaments staining intensely with hematoxylin (Figure 4). The Gram stain also showed a thin, filamentous, Gram-positive, branching organism. (Figure 5). The patient was initially treated with 10 million units of intravenous penicillin daily for two weeks, followed by oral amoxacillin/clavulanic acid. After 3 months of therapy, the clinical manifestations and radiologic findings were markedly improved (Figure 6).
Computed tomography of the chest shows patchy air-space consolidation and atelectasis of the right lower lobe.