Electron microscopic study of the orbital lesion of Hand-Schüller-Christian disease.

The orbital bone lesion of a patient with Hand-Schüller-Christian disease was examined by electron microscopy. Vacuoles in the cytoplasm of foam cells contained granules which were shown by histochemical examination to be cholesterin. Langerhans cell granules in the histiocytes of Hand-Schüller-Christian disease showed a close resemblance to those in Langerhans cell of the epidermis, eosinophilic granuloma and Letterer-Siwe disease. Charcot-Leyden crystals appeared to be formed in the lysosomes of histiocytes in Hand-Schüller-Christian disease. From histopathological and cytological points of view, eosinophilic granuloma, Hand-Schüller-Christian disease and Letterer-Siwe disease are classified as histiocytosis X. The simultaneous appearance of Langerhans cell granules and Charcot-Leyden crystals is specific in histiocytosis X.