malignant histiocytosis

A histiocyte is a differentiated tissue cell that has its origin in the bone marrow. The source for histiocytes is the monocyte/macrophage line. Monocytes (found in the blood) and macrophages (found in tissue) are responsible for phagocytosis (ingestion) of foreign material in the body. Langerhans cells are dendritic cells found in the skin and function by internalizing antigens (foreign particles) and presenting them to T cells. They arise from monocytes.{{cite journal |vauthors=Ginhoux F, Tacke F, Angeli V, Bogunovic M, Loubeau M, Dai XM, Stanley ER, Randolph GJ, Merad M |title=Langerhans cells arise from monocytes in vivo |journal=Nat. Immunol. |volume=7 |issue=3 |pages=265–73 |year=2006 |pmid=16444257 |doi=10.1038/ni1307|pmc=4727824 }} Histiocytic disorders refer to diseases that are caused by abnormal behavior of these cells. They include the following:

• Reactive diseases of Langerhans cells (most important feature in immune histochemistry is expression of E-cadherin)
• Histiocytomas
• Reactive histiocytosis (immunohistochemical features show that interstitial/dermal DCs are involved)
• Cutaneous histiocytosis (CH)
• Systemic histiocytosis (SH)
• Reactive diseases of macrophages
• Hemophagocytic syndrome – a condition where macrophages phagocytose myeloid and erythroid precursors (similar to hemophagocytic lymphohistiocytosis in humans)
• Histiocytic sarcoma complex (immunohistochemical features of dendritic cells, possibly interdigitating or perivascular DCs)
• Malignant histiocytosis
• Diffuse histiocytic sarcoma
• Localized histiocytic sarcoma
• Malignant diseases of macrophages
• Histiocytic lymphoma

Up to 25 percent of Bernese Mountain Dogs may develop malignant histiocytosis in their lifetime.E Cadieu, B Hedan, G Parker H, Gr Rutteman, A Baffoe-Bonnie, et al.. Genetics of Malignant Histiocytosis in the Bernese Mountain Dog. 3rd International Conference on Advances in Feline and Canine Genomics, 2006, UC Davis, United States. pp.Inconnu. ⟨hal-02815226⟩{{better source|reason=Conference paper not peer review journal|date=July 2020}} Other breeds with a possible genetic tendency toward malignant histiocytosis include Rottweilers, Flat-Coated Retrievers, and Golden Retrievers.{{cite book|author1=Ettinger, Stephen J. |author2=Feldman, Edward C. |title=Textbook of Veterinary Internal Medicine|edition=4th|publisher=W.B. Saunders Company|year=1995|isbn=0-7216-6795-3}}{{page number|date=July 2020}}

The disease in the lungs is characterized by enlargement of the tracheobronchial lymph nodes and infiltration of the lungs, sometimes leading to lung lobe consolidation and pleural effusion.{{cite web|author=Kessler, Martin|year=2006|title=Radiographic diagnosis of primary and metastatic lung tumors|work=Proceedings of the North American Veterinary Conference|url=http://www.ivis.org/proceedings/navc/2006/SAE/275.pdf?LA=1|access-date=2007-01-28|url-status=dead|archive-url=https://web.archive.org/web/20070929105002/http://www.ivis.org/proceedings/navc/2006/SAE/275.pdf?LA=1|archive-date=2007-09-29}} Signs and symptoms include cough, loss of appetite, weight loss, anemia, and difficulty breathing.{{cite web | last = Affolter | first = Verena K. | title = Histiocytic Proliferative Diseases in Dogs and Cats | work = Proceedings of the 29th World Congress of the World Small Animal Veterinary Association | year = 2004 | url = http://www.vin.com/proceedings/Proceedings.plx?CID=WSAVA2004&PID=8600&O=Generic | access-date = 2007-01-28 }} Seizures and rear limb weakness can be seen. Invasion of the bone marrow can cause pancytopenia.{{cite journal | last = Kearns | first = Shawn Ann |author2=Ewing, Patty | title = Causes of canine and feline pancytopenia | journal = Compendium on Continuing Education for the Practicing Veterinarian | volume = 28 | issue = 2 | pages = 122–133 | publisher = Veterinary Learning Systems | date = Feb 2006 }} Diagnosis requires a biopsy.

Treatment with chemotherapy has been used with some success, particularly using lomustine, prednisone, doxorubicin, and cyclophosphamide.{{cite journal | last = Cronin | first = Kim | title = Deciphering the histiocytic code | journal = DVM | pages = 1S–8S | publisher = Advanstar Communications | date = Dec 2006 }} Because of the rapid progression of this aggressive disease, the prognosis is very poor.{{cite journal |vauthors=Affolter V, Moore P |s2cid=17366063 |title=Localized and disseminated histiocytic sarcoma of dendritic cell origin in dogs |journal=Vet Pathol |volume=39 |issue=1 |pages=74–83 |year=2002 |pmid=12102221 |doi=10.1354/vp.39-1-74}}

A similar disease is diffuse histiocytic sarcoma, a term used to designate a localized histiocytic sarcoma that has spread throughout the body. Other signs and symptoms include weight loss and loss of appetite.{{better source|reason=Website, not peer reviewed journal|date=July 2020}}

• Histiocytosis

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| DiseasesDB =

| ICD10 = {{ICD10|C|96|1|c|81}}

| ICD9 = {{ICD9|202.3}}

| ICDO = {{ICDO|9750|3}}

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| eMedicineTopic =

| MeshID = D015620

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{{Histiocytosis}}

Category:Dog diseases

Category:Lymphoid-related cutaneous conditions

Category:Histiocytosis