Most cases of bleeding caused by vascular defects alone are not severe. Frequently, the bleeding is mainly in the skin causing petechiae, ecchymoses or both.

Inherited

Hereditary haemorrhagic telangiectasia

• Autosomal dominant
• Various genetic defects underlie the disease such as mutations of the endothelial protein, endoglin.
• There are dilated microvascular swellings which appear during childhood and become more numerous in adult life.
• These telangiectasia develop in the skin, mucous membranes and internal organs. Pulmonary, hepatic, splenic and cerebral arteriovenous shunts are seen in a minority of cases and may need local treatment.
• Recurrent epistaxes are frequent and recurrent gastrointestinal tract haemorrhage may cause chronic iron deficiency anaemia.

• Treatment is with embolization, laser treatment, oestrogens, tranexamic acid and iron supplementation. Thalidomide, lenalinomide and bevcizumab (anti‐vascular endothelial growth factor) have been use to try to reduce gastrointestinal bleeding in severe cases.

Connective tissue disorders

• In the Ehlers–Danlos syndromes there are hereditary collagen abnormalities with purpura resulting from defective platelet adhesion, hyperextensibility of joints and hyperelastic friable skin.
• Pseudoxanthoma elasticum is associated with arterial haemorrhage and thrombosis. Patients may present with superficial bruising and purpura following minor trauma or after the application of a tourniquet. Bleeding and poor wound healing after surgery may be a problem.

Acquired

Senile purpura

• Caused by atrophy of the supporting tissues of cutaneous blood vessels is seen mainly on dorsal aspects of the forearms and hands.

The Henoch–Schönlein syndrome

• Usually seen in children and often follows an acute upper respiratory tract infection. It is an IgA‐mediated vasculitis. The characteristic purpuric rash accompanied by localized oedema and itching is usually most prominent on the buttocks and extensor surfaces of the lower legs and elbows. Painful joint swelling, haematuria and abdominal pain may also occur. It is usually a self‐limiting condition but occasional patients develop renal failure.

Scurvy

• In vitamin C deficiency defective collagen may cause perifollicular petechiae, bruising and mucosal haemorrhage.

Steroid purpura

• The purpura, which is associated with long‐term steroid therapy or Cushing’s syndrome, is caused by defective vascular supportive tissue.