Elephantiasis is caused by insufficiency in the lymphatic circulation. This leads to a change in the structure of the skin. It becomes thicker; pitting oedema is initially found but later the skin is thickened and hard like armour. Wart-like hyperkeratinization also occurs: this provides an excellent growth medium for microbes. Recurrent erysipelas or sequelae of an operation are common background factors. In the tropics, a deep fungal infection may also be the cause.