Serial analysis of fat-containing macrophages in bronchoalveolar lavage fluid in a patient with fat embolism syndrome

Recent studies suggest that an increase in fat-containing macrophages in br onchoalveolar lavage (BAL) fluid may be helpful in the diagnosis of fat emb olism syndrome (FES). Nevertheless, none of these studies have explored the sequential findings of BAL fluid. We report the case of a 19-year-old man admitted to our intensive care unit because of dyspnea with radiographic ev idence of bilateral alveolar infiltrate after traumatic fracture. Analysis of BAL fluid on the third hospital day revealed 8.3% fat-containing macroph ages and a lipid-laden macrophages (LLM) index of 23. Pathologic examinatio n of lung biopsy showed numerous fat globules within arterioles. For compar ison, the BAL fluid from four other patients with acute respiratory distres s syndrome (ARDS) but without FES was also analyzed. The underlying disease s leading to ARDS included Wegener's granulomatosis in one case, pneumonia in two cases, and alveolar proteinosis in one case. The percentages of fat- containing macrophages in these specimens were 1.3%, 52%, 2.3%, and 74%, re spectively. The LLM indexes were 1, 133, 3, and 243, respectively. As the p atients condition improved, the percentage of fat-containing macrophages in the BAL fluid decreased to 4.7% on the eighth hospital day and the LLM ind ex also decreased to 6. These findings suggest that the presence of fat-con taining macrophages in BAL fluid is not specific for the diagnosis of FES, but serial changes in the percentage of these cells and the LLM index may b e helpful in the follow-up of disease severity.