Evans syndrome pathophysiology
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Ammu Susheela, M.D. [2]
Overview
Evans syndrome is an autoimmune disease in which an individual's antibodies attack their own red blood cells and platelets. The exact pathogenesis of Evans syndrome is not fully understood. On gross pathology, a circumscribed mass with microscopic infiltration is a characteristic finding of Evans syndrome. On microscopic histopathological analysis, alternating fibrous and myxoid stroma of low malignant potential, and small tumor cells with scanty eosinophilic cytoplasm with round to oval nuclei with the absence of nucleoli are characteristic findings of Evans syndrome.
Pathophysiology
Pathogenesis
- Although Evans syndrome seems to be a disorder of immune regulation, the exact pathophysiology is unknown.
- Evans syndrome is an autoimmune disease in which an individual's antibodies attack their own red blood cells and platelets.[1] Both of these events may occur simultaneously or one may follow the other.[2]
- Pathophysiology of this disease involves decreased cluster of differentiation (CD)4+ T-helper cell counts, increased CD8+ T-suppressor cell counts, a decreased CD4/CD8 ratio, and reduced serum immunoglobulin G, M and A levels - indicating a complex immune dysregulation.
- Pathology of Evans syndrome resembles a combination of autoimmune hemolytic anemia and idiopathic 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. 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.
- It has been variously reported that between 10%[3] to 23%[4] of patients who have autoimmune hemolytic anemia, will also have thrombocytopenia and thus Evans syndrome. The two features may occur together or sequentially.[5]
- Depending on the pathophysiology, Evans syndrome can be primary and secondary.
Genetics
- There are no established causes for Evan's syndrome. Evans syndrome overlaps with autoimmune lymphoproliferative syndrome.
- Autoimmune lymphoproliferative syndrome is caused by a mutation in the tumor necrosis factor receptor gene superfamily member (TNFRSF6) also called CD95 or Fas gene.
Associated Conditions
- Autoimmune hemolytic anemia
- Idiopathic thrombocytopenia purpura
- Viral infection[6]
- Systemic lupus erythematosus
- Hashimoto thyroiditis
- Dermatomyositis
- Chronic inflammatory demyelinating polyneuropathy
- Autoimmune hepatitis
Gross Pathology
- On gross pathology, circumscribed mass with microscopic infiltration is a characteristic finding of Evans syndrome.
Microscopic Pathology
- On microscopic histopathological analysis, Evans syndrome may be characterized by:
- Alternating fibrous and myxoid stroma of low malignant potential
- Small tumor cells with scanty eosinophilic cytoplasm, round to oval nuclei, and no nucleoli
References
- ↑ 1.0 1.1 Evans RS, Takahashi K, Duane RT, Payne R, Liu C (1951). "Primary thrombocytopenic purpura and acquired hemolytic anemia; evidence for a common etiology". A.M.AARRAYrchives of internal medicine. 87 (1): 48–65. PMID 14782741.
- ↑ Norton A, Roberts I (2006). "Management of Evans syndrome". Br. J. Haematol. 132 (2): 125–37. doi:10.1111/j.1365-2141.2005.05809.x. PMID 16398647.
- ↑ Template:GPnotebook
- ↑ Cai JR, Yu QZ, Zhang FQ (1989). "[Autoimmune hemolytic anemia: clinical analysis of 100 cases]". Zhonghua Nei Ke Za Zhi (in Chinese). 28 (11): 670–3, 701–2. PMID 2632179.
- ↑ Ng SC (1992). "Evans syndrome: a report on 12 patients". Clinical and laboratory haematology. 14 (3): 189–93. doi:10.1111/j.1365-2257.1992.tb00364.x. PMID 1451398.
- ↑ Simon, Ole; Kuhlmann, Tanja; Bittner, Stefan; Müller-Tidow, Carsten; Weigt, Jochen; Wiendl, Heinz; Meuth, Sven G (2013). "Evans syndrome associated with sterile inflammation of the central nervous system: a case report". Journal of Medical Case Reports. 7 (1): 262. doi:10.1186/1752-1947-7-262. ISSN 1752-1947.