Lung disease in environments with water-based aerosols may be more common than usually recognized. Patients with HP often present with only subtle abnormalities and may be missed if multiple clinical abnormalities are required to document disease.

The HP diagnostic index relies less heavily on symptoms, subjective evaluations, and invasive tests than the Kenosha criteria, but both identified similar subsets of the 61 patients as having HP. The HP diagnostic index could provide a useful tool in future HP outbreaks, which are increasingly being recognized in metalworking facilities.

Postmortem examination of the lungs of 12 patients with end-stage pulmonary fibrosis revealed the frequent (nine of 12) presence of bronchiectasis. The segmental and subsegmental bronchi were dilated, tortuous, and had a convoluted appearance that resembled a string of pearls. Bronchiectasis was confined to areas of advanced fibrosis. When fibrosis was mild or when it was combined with emphysema, bronchiectasis was absent or mild. Specimen radiographs revealed that bronchiectasis frequently contributed to the radiographic appearance of honeycombing. Retrospective analysis of the plain chest radiographs obtained from five of the patients revealed evidence suggestive of bronchiectasis, but bronchiectasis was difficult to detect unless the surrounding lung was radiopaque. In two living patients with end-stage pulmonary fibrosis, bronchiectasis was much better depicted on computed tomography scans than on plain chest radiographs. In patients with pulmonary fibrosis, the presence of bronchiectasis does not necessarily imply the presence of primary bronchial disease. Rather, bronchiectasis can be a direct result of the fibrotic process.

Four patients with acute nonlymphocytic leukemia and leukocyte counts of more than 200,000/mm3 developed respiratory distress due to pulmonary leukostasis within 10–48 hours after initiation of chemotherapy. Clinically, the patients manifested fever, dyspnea, tachypnea, diffuse pulmonary rales, pleural effusions, and severe hypoxemia. Chest roentgenograms displayed diffuse pulmonary infiltrates, vascular engorgement, cardiomegaly, and pleural effusions. Three patients died from progressive respiratory failure despite ventilatory support. Pulmonary histology revealed thrombi composed of leukemic blast cells which obstructed and distended the lumens of pulmonary arterioles, capillaries, and venules. Electron microscopy studies of lung tissue showed pulmonary alveolar endothelium and basement membrane damage and interstitial edema. The pathophysiologic basis of pulmonary leukostasis and potential treatment modalities are discussed.

No abstract