Evans syndrome

Evans' Syndrome is an autoimmune disease in which an individual's antibodies attack their own RBCs as well as their platelets,^[1] both of these events may occur simultaneously or one follow on from the other.^[2] Its overall pathology approximates to a combination of the two autoimmune induced conditions: autoimmune hemolytic anemia and immune thrombocytopenic purpura.^[1]

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. Immune thrombocytopenic purpura is a condition in which the platelets in the blood 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.

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Epidemiology

Signs and symptoms

It has been variously reported that between 10%^[3] and 23%^[4] of patients who have autoimmune haemolytic anaemia, will also have thrombocytopenia and thus Evans syndrome. The two features may occur together or sequentially.^[5]

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, IgM, and IgA these findings suggest an unsuccessful autoimmune response to an unknown trigger.^[6]

Diagnosis

The diagnosis is made upon blood tests to confirm not only haemolytic anaemia and immune thrombocytopenic purpura, but also a positive direct antiglobulin test (DAT) and an absence of any known underlying aetiology.^[2]

Other antibodies may occur directed against neutrophils and lymphocytes,^[7] and "immunopancytopenia" has been suggested as a better term for this syndrome.^[8]

Treatment

Initial treatment is with glucocorticoid corticosteroids or intravenous immunoglobulin,^[9][10] and particularly in children autoimmune hemolytic anemia is often an acute illness that responds in 80% to a short steroid course.^[11]

Although the majority of cases initially respond well, the condition often relapses and immunosuppressive drugs (e.g. ciclosporin,^[12][13] mycophenolate mofetil, vincristine^[14] and danazol^[15]) are then used,^[2] or combinations of these.^[16]

A drug, Rituxan, has given some good results in acute and refractory Evans syndrome cases,^[11][17] although further relapse may occur within a year.^[2]

Surgical splenectomy is also used in some cases,^[18] but may give only transient benefit in some.^[19]

The only prospect for a permanent cure is the high-risk option of an allogeneic hematopoietic stem cell transplantation (SCT).^[20][21]

Prognosis

Evan's Syndrome is rare, serious, and has a reported mortality rate of 7%.^{[citation needed]}

It has been observed that there is a risk of developing other autoimmune problems and hypogammaglobulinemia,^[22] 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.^[23]

References

Bibliography

acquired hemolytic anemia: Autoimmune (Warm), HUS, MAHA, PNH, PCH

Purpura: Henoch-Schönlein, ITP (Evans syndrome), TTP

primary hypercoagulable state: Protein C deficiency - Protein S deficiency - Antithrombin III deficiency - Antiphospholipid syndrome - Factor V Leiden