Erdheim-Chester disease

ICD-O-3 Morphology

9749/3: Erdheim Chester Disease
Effective 2021 and later


for cases diagnosed 2021 and later

Primary Site(s)

No primary site specified
See Module 7

Abstractor Notes

This is a new reportable neoplasm for 2021. If the diagnosis is prior to 1/1/2021, it is not reportable.

Any organ or tissue can be infiltrated by Erdheim-Chester Disease.

Characteristic features on imaging studies are bilateral and symmetrical osteosclerosis of the diaphyseal and metaphyseal parts of the long bones. Osteolytic lesions may also be seen. PET/CT has a high specificity for the diagnosis of bone involvement by ECD.

Erdheim-Chester disease can be mistaken for Langerhans cell histiocytosis. Pathologic confirmation of the disease will need to be done to determine between Langerhans cell histiocytosis and Erdheim-Chester disease.

Although no treatment plans have been established, treatments for this disease include: steroids, immunotherapy, chemotherapy, radiation and surgery.

For more information, see the Histiocytosis Association website (

Diagnostic Confirmation

This histology can be determined by positive histology (including peripheral blood) with or without genetics and/or immunophenotyping. Review the Definitive Diagnostic Methods, Immunophenotyping and Genetics Data sections below, and the instructions in the Hematopoietic Manual for further guidance on assigning Diagnostic confirmation.


Not Applicable

Module Rule


Alternate Names

Lipid (cholesterol) granulomatosis
Lipoid granulomatosis
Polyostotic sclerosing histiocytosis
Rosai-Dorfman disease


Erdheim-Chester disease (ECD) is a clonal systemic proliferation of histiocytes, commonly having a foamy (xanthomatous) component, and contain Touton giant cells (considered to be a non-Langerhans cell histiocytosis).

Definitive Diagnostic Methods

Genetic testing
Histologic confirmation

Genetics Data



CD1a lacking
CD14 expression
CD68 expression
CD163 expression
S100 lacking



Transformations to

There are no known transformations

Transformations from

There are no known transformations

Corresponding ICD-9 Codes

202.6 Malignant mast cell tumors

Corresponding ICD-10 Codes

C96.2 Malignant mast cell tumor

Corresponding ICD-10-CM Codes (U.S. only)

C96.29 Other malignant mast cell neoplasm (effective October 01, 2015)

Signs and Symptoms


Diagnostic Exams

Bone scan
BRAF testing
CT (CAT) scan
PET (positron emission tomography) scan

Progression and Transformation


Epidemiology and Mortality

Age: 55-60 median age, pediatric cases rare
Incidence: less 1000 cases reported, male predominance
Survival: 32 months average


Swerdlow SH, Campo E, Harris NL, Jaffe ES, Pileri SA, Stein H, Thiele J (Eds):
WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues (Revised 4th edition)
IARC: Lyon 2017
Section: Histiocytic and dendritic cell neoplasms
Pages: 481-482

International Classification of Diseases for Oncology, Third Edition, Second Revision. Geneva: World Health Organization, 2020
Section: ICD-O-3.2 (2020) Morphological Codes

National Cancer Institute
Section: General Information About Langerhans Cell Histiocytosis (LCH)