Derm - Non-Blanching Rashes Flashcards
What causes non-blanching rashes?
Bleeding under the skin
What are petechiae and purpura?
Petechiae
Small < 3mm
Non-blnaching red spots
Caused by burst capillaries
Purpura
Larger 3-10mm
Non-blanching red-purple
Macules or papules
Caused by leaking of blood from vessels under the skin
What are the differential diagnoses for non-blanching rashes?
- Meningococcal septicaemia or other bacterial sepsis
- Henoch-Schonlein purpura
- Idiopathic thrombocytopenia purpura
- Acute leukaemias
- Haemolytic uraemic syndrome
- Mechanical
- Traumatic
- Viral illness
How does Henoch-Schoenlein purpura present?
Purpuric rash on legs and buttocks
May have abdominal or joint pain
How long does idiopathic thrombocytopenic purpura take to develop?
Several days
Child can be otherwise well
What are some signs of acute leukaemias?
Gradual development of petechiae
Anaemia
Lymphadenopathy
Hepatosplenomegaly
How do mechanical non-blanching rashes present?
Strong coughing
Vomiting
Breath holding
In superior vena cava distribution
Above the neck, most prominently around the eyes
How do non-blanching rashes occur in traumatic cases?
Tight pressure on skin
Occlusion of blood in an area leading to traumatic petechiae
What are the typical viral causes of non-blanching rashes?
Influenza
Enterovirus
What investigations can be useful for non-blanching rashes?
FBC
Anaemia- can suggest HUS or leukaemia
Low white cells can suggest neutropenic sepsis or leukaemia
Low platelets can suggest ITP or HUS
U&Es
High urea and creatinine can indicate HUS or HSP
CRP
ESR
Coagulation screen
Clottin g abnormalities
Blood culture
Meningococcal PCR
Meningococcal disease, should not delay treatment
Lumbar puncutre
Meningitis or encephalitis
BP
Hypotension can occur in HSP and HUS, or septic shock
Urine dip
Proteinuria and haematuria can suggest HSP or HUS
What should be included in a coagulation screen?
PT
APTT
INR
Fibrinogen
How are non-blanching rashes managed?
Always urgent referral and investigation
Unless clear and unconcerning cause
In cases where there is doubt patients treated for meningococcal sepsis without waiting for investigations
