These are caused by inflammatory infiltrates and small areas of necrosis and pulmonary hemorrhage. In severe larval Ascaris infections, there may be a disseminated bronchopneumonia with diffuse small nodular infiltrates (Figs. 10.32 and 10.33). Blockage of a bronchus by an adult worm may precipitate collapse and pneumonia distal to the obstruction (Fig. 10.34). The death of a migrating larva within the lung may result in a pulmonary granuloma as fibrosis forms around it; the roentgen appearance will be that of a solitary pulmonary nodule.

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Fig. 10.32. (A) Ascaris bronchopneumonia in an African child with a severe larval infection. Small nodular infiltrates are seen throughout both lungs. (Courtesy of the late Dr. Benjamin Felson, Cincinnati, Ohio.) (B) Coiled A. lumbricoides larva in an alveolus of an experimentally infected guinea pig. The surrounding interstitial infiltrate contained eosinophils and histiocytes.

Fig. 10.33. Ascariasis of the lungs, esophagus, stomach and intestines of a 6-year-old Puerto Rican boy, who was coughing up and vomiting ascarids. There is a bilateral pneumonitis caused either by migrating larvae of Ascaris within the lungs or by aspiration (A). The outlines of several adult ascarids can be seen within the stomach and splenic flexure of the colon (A and B). When contrast media is instilled into the esophagus, several ascarids are outlined in this unusual location (B).

Fig. 10.34 Adult Ascaris blocking the left main stem bronchus in a young child from Alabama with intestinal ascariasis. There is complete collapse of the left lung with shift of the heart, mediastinum, and trachea towards the left side and elevation of the left hemidiaphragm. (Courtesy of Dr. Longstreet C. Hamilton, Fairhope, Alabama).