Table 1.

Diagnostic criteria of ECD

Radiology	Radiography	Bilateral symmetric diametaphyseal osteosclerosis of long bones
	99mTc Bone Scintigraphy	Symmetric and abnormally strong 99mTc labeling of the distal ends of the long bones
Histology	Microscopic Environment	Non Langerhans histiocytes with foamy or eosinophillic cytoplasm, polymorphic granulomae and fibrosis, xanthogranulomatosis, proliferating fibroblasts, lymphocytic aggregates, Touton giant cells
	Histiocyte Immunostaining	CD68(+), CD1a(−), S-100(negative/low)*
	Histiocyte Ultrastructure	Lack of Birbeck granules

(*) Pathological confirmation of CD68(+), CD1a(−) histiocytes is both sufficient and mandatory for the diagnosis of ECD.