Haematology Flashcards
What is purpura?
Purpura is the name given to the discolouration of the skin or mucous membranes due to haemorrhage from small blood vessels.
Describe petechiae?
plural of petechia; pinpoint form of purpura presenting as red, purple or brown non-blanchable spots
i.e. small, purpuric lesions up to 2mm across
What are ecchymoses?
medical term for bruising
Describe the different types of purpura
What is this?
Steroid purpura
What is this?
Disseminated intravascular coagulation
What is this?
Vasculitis purpura
What is this?
Venous stasis purpura
What is this?
Purpura due to injury
What is this?
Leukaemia cutis
- get this when leukaemia cells infiltrate the skin
- rare
- usually asymptomatic
What is this?
Traumatic bruise / ecchymosis
What is this?
Bruising/echymosis from heparin injection sites
What is this?
Bruising/echymosis associated with skin atrophy
How can lymphadenopathy be characterised?
-
Infective vs non-infective
Infective = bacterial (beta haemolytic streptococci, staph aureus), viral (adenovirus, rhinovirus, parainfluenza), parasitic (lyme disease)
Non-infective = amyloidosis, sarcoidosis, or connective tissue disease may cause painless generalized lymphadenopathy, and malignancies. -
Inflammatory vs malignant
Inflammatory = benign reactive lymph nodes in children. Would also include bacterial, viral, parasitic infections
Malignant = leukaemia, lymphoma - Hodgkins and non-hodgkins, metastasis of other cancers.
How can splenomegaly be characterised?
First way:
* Haematological - haemolytic anaemias, leukaemias etc
* Infectious - malaria, schistosomiasis etc
* Malignant/ Tumours and cysts - heamangioma, splenic abscesses etc
* Congestive splenomegaly - liver cirrhosis
* Connective tissue disorder - SLE
Second way:
* mild
* moderate
* massive
i have put a few examples for each one. More causes will be in other BS
What are common causes of lymphadenopathy?
Inflammatory lymphadenopathy:
* infection - if recent Hx of URTI, dental problem, travel, trauma. *Viral *causes = measles, mumps, adenovirus, HPV, EBV, HIV, CMV, roseola infantum. Bacterial causes = beta-haemolytic streptococci, staphylococcus aureus - cellulitis, periodonitis, otitis externa, otitis media, sinusitis, extra-pulmonary TB. Skin infections - eczema, cradle cap.
* Autoimmune - amyloidosis, sarcoidosis, SLE, RA
* Malignancy - leukaemia, lymphoma, LN metastasis, H+N cancer, oesophageal, breast etc
* Drugs - phenytoin, allopurinol, isoniazid
nice cks
What are the functions of the spleen?
- Sequestration and phagocytosis - old/abnormal RBC are removed by macrophages
- Blood pooling platelets and red cells can be rapidly mobilised during bleeding
- Extramedullary haemopoiesis - pluripotent stem cells proliferate during haemotological stress or if the bone marrow fails
- Immunological function - some B cells and T cells are present in the spleen
What are causes of splenomegaly?
Group into mild, moderate, massive
Mild:
* Infectious hepatitis
* Endocarditis
* Infiltrative disorders - sarcoidosis
* Autoimmune diseases - autoimmune haemolytic anaemia, idiopathic thrombocytopenic purpura, SLE
Moderate
* Lymphoma
* Leukaemias
* Myeloproliferative disorders
* Liver cirrhosis with portal hypertension
* Glandular fever
Massive
* Chronic Myeloid leukaemia
* Myelofibrosis
* Malaria
* LeishManiasis
Pic added from QM and PM
What are possible mechanisms for splenomegaly (i.e. why does the spleen grow)?
- Back pressure = portal hypertension in liver disease
- Over work = making more red cells or white blood cells (because of disorder of RBC or immune condition)
- Bone marrow failure = so spleen reverts to old job of extramedullary haemopoiesis
- Infiltration by cells = cancer cells of blood origin / cancer metastasis into spleen –> cause splenomegaly
- Infiltration by other materials (granulomas) = sarcoidosis
What are causes of hyposplenism?
- splenectomy
- sickle-cell
- coeliac disease, dermatitis herpetiformis
- Graves’ disease
- systemic lupus erythematosus
- amyloid
- What are patients with hyposplenism at risk of?
- What can be done to prevent this?
- At risk of sepsis by encapsulated bacteria
- need to be immunised (vaccinated) and given life long antibiotic prophylaxis - usually oral penicillins or macrolides
Vaccines:
* pneumococcal vaccine
* annual flu vaccine
What is the mechanism of hyposplenism in sickle cell?
from QM
- sickle cells commonly sequester in the spleen and undergo phagocytosis by the reticular endothelial system leading to extravascular haemolysis.
- Commonly this leads to splenic congestion and splenomegaly.
- The spleen is necessary for phagocytosis of encapsulated bacteria.
- Consequently, due to a compromised spleen, there is reduced immune function and individuals with sickle cell disease are prone to bacteraemia.
What may be seen on blood film of patient with hyposplenism?
- Howell-Jolly bodies
- Pappenheimer bodies
- Target cells
- Siderocytes
