Divalproex sodium-induced eosinophilic pleural effusion.

Eosinophilic pleural effusion is defined as an effusion in which eosinophils constitute more than 10% of white blood cells. These effusions can be due to multiple causes with drugs being implicated as one of the etiological agents. We report a case of 48-year-old woman with seizure disorder on divalproex sodium (Depakote) who presented with dyspnea. A chest radiograph demonstrated right pleural effusion. Investigations showed peripheral blood eosinophilia with thoracocentesis revealing eosinophilic exudative pleural effusion. An extensive workup for other causes of eosinophilic pleural effusion was unrevealing. Withdrawal of Depakote resulted in resolution of the effusion.