[Histiocytosis X. Histochemical study of intracytoplasmic lipids. Apropos of 3 cases].

Histochemical study combined with differential extractions of lipids from biopsy fragments in three cases of eosinophil granuloma reveals a great amount and variety of lipidic categories existing in histiocytosis X cells : sterids, fatty-acids, triacylglycerols, phosphoglycerids, cholino-phospholipids, sphingomyelins, glycolipids. Comparison of the lipidic content of histiocytosis X cells and that of normal histiocytes, showed a preponderance of cholesterol esters in histiocytosis X contrary to the normal macrophages and alteration in phospholipidic control of cholesterol esterification. This study confirms that the histiocytosis X cells have an active and probably preferential lipid metabolism, explaining the frequent xanthomatous changes of the lesions and the intense production of various cytoplasmic membranous structures.