Hyperleucocytosis as an unusual presentation of hypereosinophilic pneumonitis with acute respiratory distress syndrome.

Idiopathic hypereosinophilic syndrome in children is a rare disease. Even with improved understanding of eosinophilic disorders and recent advances in diagnostic modalities, evaluation of hypereosinophilia remains challenging due to heterogeneous etiologic factors. In acute clinical settings, the management plan is often unclear as the condition is not encountered frequently. It is often associated with leucocytosis, but hyperleucocytosis causing multiorgan dysfunction in the absence of malignancy is rarely seen. A previously well 5-year-old boy presented to our emergency room with a 2-week history of fever, progressive cough and dyspnoea, rapidly progressing to respiratory failure and acute respiratory distress syndrome. Hyperleucocytosis with hypereosinophilia on peripheral blood film, bilateral pulmonary infiltrates on X-ray and ground glass opacities suggested hypereosinophilic syndrome with secondary acute respiratory distress syndrome. Owing to severe and rapidly increasing leucocytosis, malignancy was highly suspected, but it was ruled out along with secondary hypereosinophilic syndrome after extensive investigations, and acute respiratory distress syndrome in this child was attributed to Idiopathic Hypereosinophilic Syndrome. Eosinophilia had a dramatic response to high dose corticosteroid therapy. To conclude, in patients with hypereosinophilic syndrome, possibility of progression to acute respiratory distress syndrome should be anticipated and managed accordingly.