BRONCHOALVEOLAR LAVAGE IN ADULT SICKLE-CELL PATIENTS WITH ACUTE CHESTSYNDROME - VALUE FOR DIAGNOSTIC-ASSESSMENT OF FAT-EMBOLISM

Fat embolism of necrotic bone marrow could be a frequent cause of acut e chest syndrome (ACS) in sickle cell syndromes (SC), as suggested by postmortem findings. To check this hypothesis in living patients, we e valuated the presence of fatty macrophages recovered by bronchoalveola r lavage (BAL) in ACS. We investigated 20 consecutive cases of ACS by BAL, and identification of alveolar cells containing fat droplets was performed using oil red O (ORO), a specific neutral fat stain. The spe cificity of the method was determined on control groups, including eig ht SC patients without acute chest syndrome and 15 non-SC patients. A cut-off of > 5% of alveolar macrophages containing fat droplets was de termined from the control groups to assess the diagnosis of fat emboli sm. In 12 ACS episodes, BAL exhibited > 5% of fatty macrophages, rangi ng from 10% to 100% (median value 46.5%). In 11 cases, fat embolism wa s associated with proven (n = 8) or probable (n = 3) bone marrow infar ction, which mostly predated ACS. Eight ACS episodes were associated w ith a low percentage (less than or equal to 5%) of fatty alveolar macr ophages and could be related to a cause other than fat embolism in six episodes, such as sepsis, in-situ thrombosis, or rib infarcts generat ing hypoventilation. This study supports the diagnostic yield of BAL f or fat embolism, which can be incriminated in 60% of cases of ACS in t his adult population.