 In most cases, differential diagnoses may be distinguished from purpura fulminans by other clinical and laboratory findings.The initial appearance of purpura fulminans lesions is of well-demarcated erythematous lesions which progress rapidly to develop irregular central areas of blue-black haemorrhagic necrosis.Advancing areas of necrosis are often surrounded by a thin border of erythema that fades into adjacent unaffected skin.