A 77-year-old man presented with a two-day history of a rash covering both calves. It was associated with mild swelling and a moderate amount of pain. He was systemically well and there were no signs of bruising, haematoma, heart failure, cellulitis or deep vein thrombosis of the legs. His abdominal examination revealed no swelling or rash.
The man had a history of gastro-oesophageal reflux disease, portal hypertension of unknown aetiology without liver failure, hypertension, dyslipidaemia, transient cerebral ischaemic events, right carotid artery stenting in 2008, and past surgery for small bowel obstruction. Four months earlier he had been started on warfarin following a pulmonary embolus. His other drugs were irbesartan 300 mg once daily, esomeprazole 20 mg once daily and atorvastatin 20 mg once daily. As the patient was due to have an elective gastroscopy, his warfarin was being withdrawn. Instead he had been given three injections of enoxaparin at therapeutic doses (over 1.5 days).
The international normalised ratio was normal at 1.1, the activated partial thromboplastin time was mildly raised at 36 seconds (normal range 25–32). Full blood count, C-reactive protein, liver function tests and estimated glomerular filtration rate were normal.
Enoxaparin can cause delayed hypersensitivity reactions remote from the injection site. While the pathophysiology of these reactions is incompletely understood, clinicians should be vigilant to allow early detection of these problems.
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