In erysipelas the ear lobe is - unlike in perichondritis - also affected.
The erysipela is an infection of the skin caused by Streptococcus pyogenes. If subcutaneous tissue, fascia and muscles are affected it's called phlegmon.
Streptococcus pyogenes penetrates through defects of the skin intothe deeper layers of the skin and spreads as a phlegmon by destroying surrounding tissue. The tissue destruction is carried out by enzymes produced by bacteria such as DNAse.
Risk factors for erysipelas are chronic wounds, immune suppression and peripheral arterial occlusive disease.
Source: Klaus D. Peter, Gummersbach, Germany