Erdheim-Chester disease laboratory findings

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Histologically, ECD differs from Langerhans cell histiocytosis (LCH) in a number of ways. Unlike LCH, ECD does not stain positive for S-100 or CD 1a, and electron microscopy of cell cytoplasm does not disclose Birbeck granules.^[1] Tissue samples show xanthomatous or xanthogranulomatous infiltration by lipid-laden or foamy histiocytes, and are usually surrounded by fibrosis. Bone biopsy is said to offer the greatest likelihood of reaching a diagnosis.

ECD is not a common cause of exophthalmos but can be diagnosed by biopsy. However, like all biopsies, this may be inconclusive.^[2]