Valproic Acid Induced Pleural Effusion: A Rare Clinical and Pathophysiological Entity

Introduction: Among the reported cases of valproic acid - induced pleural effusion, recurrence of pleural fluid accumulation has scarcely been presented in the literature. Case presentation: This case study reports a 51-year-old man under treatment with valproic acid, who presented with recurrent pleural effusion characterized by transition from eosinophilic to lymphocytic predominance. The recurrence of the effusion upon re-administration of the drug, along with its resolution upon discontinuation of treatment with valproic acid, is strongly indicative of a causative association. Conclusion: This is the first reported case of recurrent valproic acid - induced pleural effusion presenting with transition from eosinophilic to lymphocytic predominance. We aim to highlight the importance of taking into consideration the causative role of valproic acid in inducing pleural effusion, even when the pleural fluid demonstrates alteration in the predominant cell type.