A case of tropical eosinophilia associated with pleural effusion

A 52-year-old man was admitted to Keio University Hospital for determination of the etiology of a bilateral pleural effusion associated with marked eosinophilia (10200 cells/mm³). He had been in Vietnam for three years and had returned to Japan in May 1993. He was suffering from tropical eosinophilia, as clearly indicated by eosinophilia, elevation of serum IgE level (708 IU/ml), the presence of anti-dirofilarial antibodies, and the absence of microfilaria in the blood. The pleural effusion was an exudate and 51% of the cells in the effusion were eosinophils. In the effusion, no parasites were detected but anti-dirofilarial antibodies were found (the titer was as high as that in the serum). Diethylcarbamazine was given, and a steroid had to be superimposed because of wheezing. These treatments successfully reduced the bronchoconstriction, eosinophilia and accumulation of pleural effusion. Tropical eosinophilia has generally been thought not to be associated with pleural effusion. This is only the third case report of tropical eosinophilia with authentic pleural effusion.