Congenital histiocytosis X.

Congenital histiocytosis X involving multiple organs is a rare disease that causes rapid mortality in intrauterine and neonatal life. The diagnosis of histiocytosis X (Letterer-Siwe disease) should be considered in a neonate with vesiculated crusting skin lesions. We present clinical, radiographic and histopathological findings in a neonate with congenital histiocytosis who died of respiratory failure due to diffuse infiltration of lungs with histiocytic cells.