Differential diagnosis of purpura fulminans

This has come up in Question 14.2 from the second paper of 2010.
The question ("What the hell is this?") was accompanied by an image which resembles the one below:

That is purpura fulminans, resulting - in this case - from menigococcal sepsis.

The image was stolen shamelessly from www.unboundedmedicine.com to replace the college's proprietary purpura picture.

A less florid (and therefore more common) appearance in an asplenic adult can be seen below:

Purpura fulminans in an asplenic adult

If this ever comes up again, it is likely that the college will expect the candidates to generate a list of differentials to explain this appearance.

Thus:

Causes of Purpura Fulminans

Infective

Non-infective

  • DIC from any cause
  • MAHA (microangiopathic haemolytic anaemia)
  • TTP (thrombotic thrombocytopenic purpura)
  • Vasopressor excess
  • Warfarin-induced skin necrosis
  • Congenital Protein C anticoagulant pathway defect
  • Post-infectious purpura fulminans (due to autoimmune destruction of proteins C or S)
   

References

Gürses, Nuran, and Ismail Ilek. "Causes of purpura fulminans." The Pediatric infectious disease journal 14.6 (1995): 552.

Spicer, Thomas E., and Jerold M. Rau. "Purpura fulminans." The American journal of medicine 61.4 (1976): 566-571.

Chalmers, E., et al. "Purpura fulminans: recognition, diagnosis and management." Archives of disease in childhood 96.11 (2011): 1066-1071.