Thoraco-pleural actinomycosis presenting like diffuse pulmonary embolism.

Actinomycosis is an uncommon infection. The regions mostly involved are the cervico fascial area, the thorax and the abdomen. The thoracic variety accounts for approximately 15% of the cases. Clinical pictures of pulmonary neoplasm, abscess, and empyema have been described. Misleading symptoms often delay the right diagnosis. The present study describes a case of actinomycosis with pleuro-pulmonary involvement. A 48-year woman had been well until two and a half years previously, when she developed symptoms suggestive of pneumonia. When referred to a medical clinic with thoracic pain and tiredness, pulmonary embolism was suspected. Inhalation and perfusion scintigraphy showed several perfusion defects. There were several relapses, with clinical pictures suggestive of pulmonary embolism, before an abscess in the left axilla appeared. Drained pus showed no growth of Actinomycetes. Correct diagnosis of the true cause was only possible by direct microscopy. Possible symptoms and the diagnostic difficulties when Actinomycetes is involved are discussed.