Autoimmune Haematological Disorders



Autoimmune Haematological Disorders






Immune thrombocytopenia (ITP)


Presentation



  • ITP can occur at any age and is characterized by thrombocytopenia, with increased marrow megakaryocytes, and shortened platelet survival.


  • Presentation is usually with sudden onset of petechiae, particularly around the feet, and bleeding (nose, gums, bowel, urinary tract).



    • Can occur with:


    • infection (including HIV)


    • drugs (the list is very long!)


    • malignancy (lymphoma, adenocarcinoma)


    • common variable immunodeficiency


    • other autoimmune diseases (SLE, thyroid disease, autoimmune hepatitis).


  • Neonatal alloimmune thrombocytopenia may occur in mothers who are negative for the platelet antigen PLA1, who become sensitized in prior pregnancies where infants are PLA1 positive or by blood transfusion; other platelet antigen systems have also been involved.


Immuno pathology



  • Antibody-coated platelets are destroyed by the phagocytic cells in the peripheral blood.


  • Many platelet antigens have been shown to be targets for the autoimmune response, including GPIIb/IIIA, GPIb/IX and GP V (after chickenpox).


  • Detection of anti-platelet antibodies is difficult and few centres offer this routinely.


  • A wide variety of tests are used.


Diagnosis (see Box 9.1)



  • Diagnosis can usually be made clinically, with the assistance of a bone marrow examination.


  • Investigations are needed to rule out associated autoimmune disease (SLE), immunodeficiency, and malignancy.


  • Drug history should be reviewed.





Autoimmune haemolytic anaemia


Classification

Immune haemolytic anaemia is divided into two categories depending on the temperature at which haemolysis takes place.



  • Warm haemolytic anaemia:



    • idiopathic autoimmune (AIHA)


    • secondary to other diseases—SLE, CVID, lymphoid malignancy, hepatitis.


  • Cold haemolytic anaemia:



    • idiopathic cold agglutinin disease


    • cold agglutinins secondary to infection (Mycoplasma pneumoniae, EBV)


    • cold antibody disease (Donath-Landsteiner antibody, occurs in childhood or secondary to syphilis)—paroxysmal cold haemoglobinuria


    • cold antibody disease secondary to lymphoma (CHAD).


  • Other causes of haemolytic anaemia include:



    • drug-induced (which may be due to bystander immune-complex-mediated damage or direct binding of antigen (e.g. penicillin) to the red cell membrane causing the formation of an immunoreactive neo-antigen)


    • massive haemolysis may occur following mismatched blood transfusions (ABO incompatibility, preformed isoagglutinins)


    • as a result of rhesus incompatibility (rhesus haemolytic disease of the newborn); in association with ITP (Evans syndrome).


Presentation



  • Depends on the underlying cause.


  • Signs of anaemia ± jaundice will usually be the presentation.



Diagnosis (see Box 9.2)

Jul 22, 2016 | Posted by in GENERAL SURGERY | Comments Off on Autoimmune Haematological Disorders

Full access? Get Clinical Tree

Get Clinical Tree app for offline access