immunology case part 5

Question 1

How do petechial rash look like?

Answer 1

small, red-brown, flat macules up to 2 mm in diameter which do not blanch when pressure is applied. They are caused by tiny spots of blood gathered under the surface of the skin.

Question 2

what is thrombocytopenia?

Answer 2

low platelets

Question 3

how is a platelet plug formed?

Answer 3

1. vasoconstriction
2. vWF released from damaged endothelium binds to exposed collagen in sub endothelium
3. platelets adhere to VWF and collagen
4. platelet activation, shape change and degranulation occur
5. GPIIb/IIIa receptors on platelet surface now exposed and able to bind to fibrinogen
6. Aggregation occurs by many platelets linking together via fibrinogen

Question 4

what are the 2 classification of causes of thrombocytopenia

Answer 4

1. decreased production of plateleyts

2. Increased consumption and/or destruction of platelets

Question 5

causes of decrease production of platelets?

Answer 5

inherited bone marrow failure syndromes

acute leukaemia

metastatic cancer spread to the bone

liver cirrhosis

chemotherapy

immune thrombocytopenia purpura

Question 6

causes of increased consumption or destruction of platelets

Answer 6

immune thrombocytopenia purpura

liver cirrhosis

disseminated intravascular coagulation

thrombotic thrombocytopenia purpura

Question 7

what are the clinical signs of thrombocytopenia?

Answer 7

• Purpura
• Pallor
• Retinal haemorrhage
• Blood blisters
• Easy or excessive bruising

Question 8

what are some additional signs suggesting of thrombocytopenia?

Answer 8

• Spider Naevi
• Palmer erythema
• Hepatomegaly
• Spelenomegaly
• Lymphadenopathy
• Jaundice
• Gum hypertrophy
• Pallor
• Candidiasis
• Peripheral neuropathy
• Glossitis

Question 9

3 ddx of thrombocytopenia?

Answer 9

1. B12 deficiency
2. Chronic liver disease
3. Haematological malignancy

Question 10

what is immune thrombocytopenia purpura?

Answer 10

isolated thrombocytopenia in the absence of an alternative identifiable cause

Question 11

most important initial treatment for immune thrombocytopenia purpura?

Answer 11

1. Oral corticosteroids

Thrombopoietin analogues- not 1st but use if unresponsive to other options

platelet transfusion only if very severe and has active bleeding or is at risk

Splenectomy: is a second line treatment and as the patient has no history of ITP, this would be inappropriate and hazardous with a low platelet count.