This stage is characterized by the presence of necrosis (gangrene) which has grave implications, threatening the loss of the limb. Necrosis can involve skin, subcutaneous and fascial layers. In lightly pigmented skin it is easily evident but in the subcutaneous and fascial layers it is not so apparent. Furthermore, the extent of necrosis may be difficult to determine: often the bluish-black discolouration of skin is just the 'tip of an iceberg' of massive necrosis.
Other conditions may masquerade as necrosis (see Chapter 1). Purplish-black or brown discolouration of the skin also occurs after bruising and is sometimes difficult to differentiate from early necrosis associated with a history of trauma. A superficial collection of dried blood within a blister or tracking under the skin can give part of a foot a black and leathery appearance. Cyanosis of toes and feet is seen in severe cardiac and respiratory failure.
Shoe dye and the application of topical henna will result in black or brown discolouration of the skin.
Was this article helpful?