Orbital sinus histiocytosis: MR appearance.

This case report describes the appearance of orbital sinus histiocytosis by magnetic resonance (MR) imaging. Four years after the remission of unilateral cervical adenopathy due to sinus histiocytosis, a 6-year-old girl developed orbital sinus histiocytosis with extension into the middle cranial fossa. Computed tomography demonstrated a homogeneously enhancing lesion; on MR, this tumor was isointense to gray matter on T1-weighted, proton density, and T2-weighted images. Vascular embarrassment was clearly shown by MR.