Radionuclide bone scintigraphy in patients with histiocytosis X

The term histiocytosis X (HX) refers to a spectrum of disorders varying from unifocal eosinophilic granuloma (UEG), multifocal eosinophilic granuloma (MEG), to the Abt-Letterer-Siwe syndrome. In a series of 16 patients with different types of HX and skeletal lesions, whole body bone scintigraphy was performed at the time of diagnosis and during follow up. Results were compared with radiographic findings. In patients with MEG with or without extra-skeletal dissemination bone scintigraphy revealed cold spots or hot spots, but half of the lesions were not visualised scintigraphically, resulting in false negative scans. In UEG the lesions were visualised as areas of increased uptake or as a cold spot with increased uptake at its borders. No false negative scans were encountered. The reliability of skeletal scintigraphy in patients with HX seems to depend on the type of the disorder: in UEG bone scintigraphy is a safe procedure. In MEG false negative bone scans have to be expected, and radiography is superior.