sinus histiocytosis some radiologic observations sinus histiocytosis with massive lymphadenopathy is an unusual disease characterized by prominent lymph node enlargement especially in the cervical region the clinical course is benign although prolonged and no specific treatment is required the etiology and pathogenesis are unknown four cases of sinus histiocytosis are reported one in association with mediastinal lymph node enlargement and two in patients with orbital enlargement one other patient had cervical masses the radiologic features are reviewed to increase awareness of this entity as a cause of lymph node and orbital enlargement the estimation of midazolam a watersoluble benzodiazepine by gas liquid chromatography a simple reliable and reproducible method for the estimation of midazolam in plasma samples is described this involves extraction with benzene and estimation by gasliquid chromatography using diazepam as the internal standard reproducibility was good and the extraction from plasma was 94 efficient