Erdheim-Chester disease diagnostic criteria23
| Clinical or morphological |
| 1. Symmetric diaphyseal and metaphyseal osteosclerosis in the legs; best seen by PET scan |
| 2. Other typical ECD findings: perirenal infiltration or periaortic sheathing (CT), right atrial pseudotumor (MRI), or physical examination findings of xanthelasma, exophthalmos, or osteosclerosis of facial sinuses |
| Histopathological |
| 1. Foamy or lipid-laden histiocytes, fibrosis, and sometimes Touton giant cells |
| 2. Staining for CD68 or CD163 and negative for CD1a |
| Molecular |
| 1. BRAFV600E mutation |
| 2. Other activating mutations of the MAPK pathway: KRAS, NRAS, MaP2K1, ARAF, MAP3KI, and others |
| 3. Gene fusion activating the MAPK pathway or |
| 4. Activating mutation in CSF1R |
| Clinical or morphological |
| 1. Symmetric diaphyseal and metaphyseal osteosclerosis in the legs; best seen by PET scan |
| 2. Other typical ECD findings: perirenal infiltration or periaortic sheathing (CT), right atrial pseudotumor (MRI), or physical examination findings of xanthelasma, exophthalmos, or osteosclerosis of facial sinuses |
| Histopathological |
| 1. Foamy or lipid-laden histiocytes, fibrosis, and sometimes Touton giant cells |
| 2. Staining for CD68 or CD163 and negative for CD1a |
| Molecular |
| 1. BRAFV600E mutation |
| 2. Other activating mutations of the MAPK pathway: KRAS, NRAS, MaP2K1, ARAF, MAP3KI, and others |
| 3. Gene fusion activating the MAPK pathway or |
| 4. Activating mutation in CSF1R |