Evans syndrome
Encyclopedia
Evans syndrome is an autoimmune disease
in which an individual's antibodies attack their own red blood cell
s and platelet
s. Both of these events may occur simultaneously or one follow on from the other.
Its overall pathology resembles a combination of autoimmune hemolytic anemia
and idiopathic thrombocytopenic purpura
. Autoimmune hemolytic anemia is a condition in which the red blood cells that normally carry oxygen
and carbon dioxide
are destroyed by an autoimmune process. Idiopathic thrombocytopenic purpura is a condition in which platelets are destroyed by an autoimmune process. Platelets are a component of blood that contribute to the formation of blood clots in the body to prevent bleeding.
The syndrome was first described in 1951 by R. S. Evans and colleagues.
, and IgA
these findings suggest an unsuccessful autoimmune response to an unknown trigger.
(DAT) and an absence of any known underlying aetiology.
Other antibodies may occur directed against neutrophils and lymphocytes, and "immunopancytopenia" has been suggested as a better term for this syndrome.
corticosteroid
s or intravenous immunoglobulin
, a procedure that is also used in ITP cases. In children, good response to a short steroid course is achieved in approximately 80 percent of cases. Although the majority of cases initially respond well to treatment, relapses are not uncommon and immunosuppressive drugs (e.g. ciclosporin
, mycophenolate mofetil
, vincristine
and danazol
) are subsequently used, or combinations of these.
The off-label use of rituximab
(trade name Rituxan) has produced some good results in acute and refractory cases, although further relapse may occur within a year. Splenectomy
is effective in some cases, but relapses are not uncommon.
The only prospect for a permanent cure is the high-risk option of an allogeneic hematopoietic stem cell transplantation (SCT).
It has been observed that there is a risk of developing other autoimmune problems and hypogammaglobulinemia
, with recent research finding that 58% of children with Evans syndrome have CD4-/CD8- T cells which is a strong predictor for having autoimmune lymphoproliferative syndrome
.
Autoimmune disease
Autoimmune diseases arise from an overactive immune response of the body against substances and tissues normally present in the body. In other words, the body actually attacks its own cells. The immune system mistakes some part of the body as a pathogen and attacks it. This may be restricted to...
in which an individual's antibodies attack their own red blood cell
Red blood cell
Red blood cells are the most common type of blood cell and the vertebrate organism's principal means of delivering oxygen to the body tissues via the blood flow through the circulatory system...
s and platelet
Platelet
Platelets, or thrombocytes , are small,irregularly shaped clear cell fragments , 2–3 µm in diameter, which are derived from fragmentation of precursor megakaryocytes. The average lifespan of a platelet is normally just 5 to 9 days...
s. Both of these events may occur simultaneously or one follow on from the other.
Its overall pathology resembles a combination of autoimmune hemolytic anemia
Autoimmune hemolytic anemia
Autoimmune hemolytic anemia occurs when antibodies directed against the person's own red blood cells cause the RBCs to burst , leading to insufficient plasma concentration. The lifetime of the RBCs is reduced from the normal 100–120 days to just a few days in serious cases...
and idiopathic thrombocytopenic purpura
Idiopathic thrombocytopenic purpura
Idiopathic thrombocytopenic purpura is the condition of having an abnormally low platelet count of no known cause . As most incidents of ITP appear to be related to the production of antibodies against platelets, immune thrombocytopenic purpura or immune thrombocytopenia are terms also used to...
. Autoimmune hemolytic anemia is a condition in which the red blood cells that normally carry oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
and carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
are destroyed by an autoimmune process. Idiopathic thrombocytopenic purpura is a condition in which platelets are destroyed by an autoimmune process. Platelets are a component of blood that contribute to the formation of blood clots in the body to prevent bleeding.
The syndrome was first described in 1951 by R. S. Evans and colleagues.
Signs and symptoms
It has been variously reported that between 10% and 23% of patients who have autoimmune haemolytic anaemia, will also have thrombocytopenia and thus Evans syndrome. The two features may occur together or sequentially.Causes
The precise cause is not yet known, but the immunology does differ from patients with just ITP with decreased T4 (T-helper), increased T8 (T-suppressor) and a decreased T4:T8 ratio. Together with decreased serum levels of IgG, IgMIGM
IGM as an acronym or abbreviation can refer to:* Immunoglobulin M , the primary antibody against A and B antigens on red blood cells* International Grandmaster, a chess ranking* intergalactic medium* Intragroup medium - see: Intracluster medium...
, and IgA
IGA
Iga or IGA may stand for:-Given name:* a female given name of Polish origin. The name originates from the female given name Jadwiga and stands for gia,or gina in the USA....
these findings suggest an unsuccessful autoimmune response to an unknown trigger.
Diagnosis
The diagnosis is made upon blood tests to confirm not only haemolytic anaemia and idiopathic thrombocytopenic purpura, but also a positive direct antiglobulin testCoombs test
Coombs test refers to two clinical blood tests used in immunohematology and immunology...
(DAT) and an absence of any known underlying aetiology.
Other antibodies may occur directed against neutrophils and lymphocytes, and "immunopancytopenia" has been suggested as a better term for this syndrome.
Treatment
Initial treatment is with glucocorticoidGlucocorticoid
Glucocorticoids are a class of steroid hormones that bind to the glucocorticoid receptor , which is present in almost every vertebrate animal cell...
corticosteroid
Corticosteroid
Corticosteroids are a class of steroid hormones that are produced in the adrenal cortex. Corticosteroids are involved in a wide range of physiologic systems such as stress response, immune response and regulation of inflammation, carbohydrate metabolism, protein catabolism, blood electrolyte...
s or intravenous immunoglobulin
Intravenous immunoglobulin
Intravenous immunoglobulin is a blood product administered intravenously. It contains the pooled IgG extracted from the plasma of over one thousand blood donors. IVIG's effects last between 2 weeks and 3 months...
, a procedure that is also used in ITP cases. In children, good response to a short steroid course is achieved in approximately 80 percent of cases. Although the majority of cases initially respond well to treatment, relapses are not uncommon and immunosuppressive drugs (e.g. ciclosporin
Ciclosporin
Ciclosporin , cyclosporine , cyclosporin , or cyclosporin A is an immunosuppressant drug widely used in post-allogeneic organ transplant to reduce the activity of the immune system, and therefore the risk of organ rejection...
, mycophenolate mofetil
Mycophenolate mofetil
Mycophenolate mofetil is an immunosuppressant and prodrug of mycophenolic acid, used extensively in transplant medicine. It is a reversible inhibitor of inosine monophosphate dehydrogenase in purine biosynthesis, which is necessary for the growth of T cells and B cells...
, vincristine
Vincristine
Vincristine , formally known as leurocristine, sometimes abbreviated "VCR", is a vinca alkaloid from the Catharanthus roseus , formerly Vinca rosea and hence its name. It is a mitotic inhibitor, and is used in cancer chemotherapy.-Mechanism:Tubulin is a structural protein that polymerizes to...
and danazol
Danazol
Danazol is a derivative of the synthetic steroid ethisterone, a modified testosterone. Also known as 17alpha-ethinyl testosterone. Before becoming available as a generic drug, Danazol was marketed as Danocrine in the United States. It was approved by the U.S. Food and Drug Administration as the...
) are subsequently used, or combinations of these.
The off-label use of rituximab
Rituximab
Rituximab, sold under the trade names Rituxan and MabThera, is a chimeric monoclonal antibody against the protein CD20, which is primarily found on the surface of B cells...
(trade name Rituxan) has produced some good results in acute and refractory cases, although further relapse may occur within a year. Splenectomy
Splenectomy
A splenectomy is a surgical procedure that partially or completely removes the spleen.-Indications:The spleen, similar in structure to a large lymph node, acts as a blood filter. Current knowledge of its purpose includes the removal of old red blood cells and platelets, and the detection and fight...
is effective in some cases, but relapses are not uncommon.
The only prospect for a permanent cure is the high-risk option of an allogeneic hematopoietic stem cell transplantation (SCT).
Prognosis
Evan's syndrome is rare, serious, and has a reported mortality rate of seven percent.It has been observed that there is a risk of developing other autoimmune problems and hypogammaglobulinemia
Hypogammaglobulinemia
Hypogammaglobulinemia is a type of immune disorder characterized by a reduction in all types of gamma globulins.Hypogammaglobulinemia is a characteristic of common variable immunodeficiency.-Terminology:...
, with recent research finding that 58% of children with Evans syndrome have CD4-/CD8- T cells which is a strong predictor for having autoimmune lymphoproliferative syndrome
Autoimmune lymphoproliferative syndrome
Autoimmune lymphoproliferative syndrome is a form of lymphoproliferative disorder. It affects lymphocyte apoptosis. It is a RASopathy.-Introduction:...
.