ABC of arterial and venous disease. Ulcerated lower limb.

Venous disease, arterial disease, and neuropathy cause over 90% of lower limb ulcers. It is useful to divide leg ulcers into those occurring in the gaiter area and those occurring in the forefoot because the aetiologies in these two sites are different. At least two aetiological factors can be identified in one third of all lower limb ulcers. Venous ulcers most commonly occur above the medial or lateral malleoli. Arterial ulcers often affect the toes or shin or occur over pressure points. Neuropathic ulcers tend to occur on the sole of the foot or over pressure points. Apart from necrobiosis lipoidica, diabetes is not a primary cause of ulceration but often leads to ulceration through neuropathy or ischaemia, or both. The possibility of malignancy, particularly in ulcers that fail to start healing after adequate treatment, should always be borne in mind. The commonest malignancies are basal cell carcinoma, squamous cell carcinoma, and melanoma. Patients with reduced mobility or obesity may develop ulceration in the gaiter area because of venous hypertension resulting from inadequate functioning of the calf muscle pump. The commonest causes of vasculitic ulcers are rheumatoid arthritis, systemic lupus, and polyarteritis nodosa. The blood dyscrasias that most commonly lead to leg ulceration are sickle cell disease, thalassaemia, thrombocythaemia, and polycythaemia rubra vera.