Dendritic Cell Neoplasms

Please note the following are subject to change until the time of release.

Summary of changes made to <<1186648002 |Histiocytic proliferation (morphologic abnormality)|:

The <<1186648002 |Histiocytic proliferation (morphologic abnormality)| hierarchy and associated disorder concepts were reviewed by the Histology Quality Improvement Project Group. Content was revised based on the Blue Book 5th edition ‘Histiocytic/dendritic cell neoplasms’ chapter and SNOMED CT editorial guidelines. Below are more details about the proposed changes.
Note: The xanthogranuloma content was not addressed during this work. We determined it needs further review and input from the community before remodeling. 

Key changes:

1. Langerhans’ cell histiocytosis (LCH) is either Single system (SS-LCH) or Multisystem (disseminated) LCH.

   SS-LCH is /1 behaviour
   MS-LCH is /3 behaviour

2. Eosinophilic granuloma is obsolete.  However, it is a SS-LCH.  Disorders defined by eosinophilic granuloma are remodeled and renamed using SS-LCH.  Eosinophilic granuloma is retained as a synonym.

3. Rosai-Dorfman disease and Pulmonary hypertension in LCH were remodeled to more correctly represent the disorders.

4. Key notes:

   1. Disorders using LCH (NOS) as the defining morphology are left unchanged even if the Finding site is a single organ. Technically, they could be remodeled using SS-LCH as only a single system is defined.  However, too much ambiguity exists to categorically make this change.

   2. Disorders using MS-LCH/disseminated LCH are left unchanged even though most concepts only define a single system…which could infer SS-LCH.  It is clear, however, that these are disseminated LCH.  The systems are nodal areas, and the diagnostician intentionally is stating disseminated. So, no changes were done to prevent disruption in historical data.

List of concepts added or inactivated:

1.  19 new concepts added: 

   1. 1373783006|Histiocytic macrophage neoplasm (disorder)

   2. 1380198008|Benign littoral cell angioma (morphologic abnormality)

   3. 1380199000|Benign sclerosing angiomatoid nodular transformation of spleen (morphologic abnormality)

   4. 1373338008|Langerhans cell neoplasm (morphologic abnormality)

   5. 1373341004|Histiocytic macrophage neoplasm (morphologic abnormality)

   6. 1373377006|Malignant dendritic cell neoplasm (morphologic abnormality)

   7. 1380408006|Malignant EBV-positive inflammatory follicular dendritic cell sarcoma (morphologic abnormality)

   8. 1380196007|Malignant hematopoietic sarcoma (morphologic abnormality)

   9. 1373423008|Malignant ALK-positive histiocytosis (morphologic abnormality)

   10. 1380195006|Malignant mesenchymal sarcoma (morphologic abnormality)

   11. 1380200002|Malignant mesenchymal dendritic cell neoplasm (morphologic abnormality)

   12. 1396874009|Malignant histiocytic macrophage neoplasm (morphologic abnormality)

   13. 1399256008 |Malignant histiocytic macrophage neoplasm (disorder)|

   14. 1373340003|Plasmacytoid dendritic cell neoplasm (morphologic abnormality)

   15. 1380193004|Mesenchymal neoplasm (morphologic abnormality)

   16. 1373346009|Mature plasmacytoid dendritic cell proliferation associated with myeloid neoplasm (morphologic abnormality)

   17. 1380194005|Stroma derived neoplasm of lymphoid tissue (morphologic abnormality)

   18. 1380197003|Splenic vascular stromal tumor (morphologic abnormality)

   19. 1402004007 |Malignant histiocytic macrophage neoplasm of skin (disorder)|

2. 13 concepts inactivated: