Hemophagocytic lymphohistiocytosis: Difference between revisions
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===Familial forms=== | ===Familial forms=== | ||
FHL, an [[autosomal recessive]] disorder, is invariably fatal when untreated. It is associated with defective triggering of [[apoptosis]] and reduced cytotoxic activity, resulting in a widespread accumulation of T lymphocytes and activated macrophages. | FHL, an [[autosomal recessive]] disorder, is invariably fatal when untreated. It is associated with defective triggering of [[apoptosis]] and reduced cytotoxic activity, resulting in a widespread accumulation of T lymphocytes and activated macrophages. | ||
There are four types, and each is associated with a specific gene: | There are four types, and each is associated with a specific gene: | ||
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[[Image:autorecessive.jpg|thumb|left|Familial hemophagocytic lymphohistiocytosis has an autosomal recessive pattern of inheritance.]] | [[Image:autorecessive.jpg|thumb|left|Familial hemophagocytic lymphohistiocytosis has an autosomal recessive pattern of inheritance.]] | ||
<br clear="left"/> | <br clear="left"/> | ||
==Pathophysiology== | ==Pathophysiology== | ||
Excessive production of too many activated immune cells ([[lymphocytes]]) called [[T cells]], [[natural killer cells]], [[B cells]], and [[macrophages]] ([[histiocytes]]) and [[cytokines]] by the immune system causes symptoms and damages [[liver]] and [[spleen]] and causes these organs to enlarge. Familial hemophagocytic lymphohistiocytosis also destroys blood-producing cells in the bone marrow, a process called hemophagocytosis. As a result, affected individuals have low numbers of red blood cells (anemia) and a reduction in the number of blood cells involved in clotting (platelets). A reduction in platelets may cause easy bruising and abnormal bleeding. | Excessive production of too many activated immune cells ([[lymphocytes]]) called [[T cells]], [[natural killer cells]], [[B cells]], and [[macrophages]] ([[histiocytes]]) and [[cytokines]] by the immune system causes symptoms and damages [[liver]] and [[spleen]] and causes these organs to enlarge. Familial hemophagocytic lymphohistiocytosis also destroys blood-producing cells in the bone marrow, a process called hemophagocytosis. As a result, affected individuals have low numbers of red blood cells ([[anemia]]) and a reduction in the number of blood cells involved in clotting (platelets). A reduction in platelets may cause easy bruising and abnormal [[bleeding]]. | ||
==Diagnosis== | ==Diagnosis== | ||
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===Symptoms=== | ===Symptoms=== | ||
* [[Fever]] | |||
* [[Rash]] on the skin | * [[Rash]] on the skin | ||
* [[Abdominal pain]] | * [[Abdominal pain]] | ||
* | * Abnormal [[bleeding]] | ||
== References == | == References == | ||
Revision as of 02:23, 1 August 2012
| Hemophagocytic lymphohistiocytosis | |
 | |
|---|---|
| Light microscopic image of bone marrow showing stromal macrophages containing numerous red blood cells in their cytoplasm | |
| ICD-10 | D76.1 |
| ICD-9 | 288.4 |
| OMIM | 267700 603552 |
| DiseasesDB | 31418 |
| MeSH | D051359 |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Raviteja Guddeti, M.B.B.S. [2]
Synonyms and keywords: Hemophagocytic syndrome, Familial histiocytic reticulosis, Hemophagocytic lymphohistiocytosis - familial, Erythrophagocytic lymphohistiocytosis - familial, Familial haemophagocytic lymphohistiocytosis
Overview
Hemophagocytic lymphohistiocytosis (HLH)[1] is an uncommon hematologic disorder in which the immune system produces too many activated immune cells (lymphocytes) called T cells, natural killer cells, B cells, and macrophages (histiocytes). Excessive amounts of immune system proteins called cytokines are also produced.
Classification
HLH comprises
- Familial (primary) hemophagocytic lymphohistiocytosis (FHL)
- Secondary HLH (SHLH)
Familial forms
FHL, an autosomal recessive disorder, is invariably fatal when untreated. It is associated with defective triggering of apoptosis and reduced cytotoxic activity, resulting in a widespread accumulation of T lymphocytes and activated macrophages.
There are four types, and each is associated with a specific gene:
Pathophysiology
Excessive production of too many activated immune cells (lymphocytes) called T cells, natural killer cells, B cells, and macrophages (histiocytes) and cytokines by the immune system causes symptoms and damages liver and spleen and causes these organs to enlarge. Familial hemophagocytic lymphohistiocytosis also destroys blood-producing cells in the bone marrow, a process called hemophagocytosis. As a result, affected individuals have low numbers of red blood cells (anemia) and a reduction in the number of blood cells involved in clotting (platelets). A reduction in platelets may cause easy bruising and abnormal bleeding.
Diagnosis
History
Inquiry about family history may help diagnose the familial forms of Hemophagocytic lymphohistiocytosis.
Symptoms
- Fever
- Rash on the skin
- Abdominal pain
- Abnormal bleeding
References
- ↑ Fisman DN (2000). "Hemophagocytic syndromes and infection". Emerging Infect. Dis. 6 (6): 601–8. doi:10.3201/eid0606.000608. PMC 2640913. PMID 11076718.
- Fisman DN (2000). "Hemophagocytic syndromes and infection". Emerging Infect. Dis. 6 (6): 601–608. PMID 11076718.
- Henter JI, Samuelsson-Horne A, Aricò M; et al. (2002). "Treatment of hemophagocytic lymphohistiocytosis with HLH-94 immunochemotherapy and bone marrow transplantation". Blood. 100 (7): 2367–2373. doi:10.1182/blood-2002-01-0172. PMID 12239144.
External links
- http://www.hrtrust.org/library/HLHSymptomsSignsAndDiagnosis.html
- Histiocytosis at eMedicine
- http://www.histio.org
- http://www.jonahchuang.com
- http://www.elyseyu.com
- http://www.ethanmichaelsmith.com
- http://www.savejonah.com