Bullous Eruption of the Lower Limbs Following Equine Phenylbutazone Injection

This 50-year-old female stable owner, recently widowed, was found comatose with large intact blisters on the sole of the right foot, dorsum of the right foot, and the left shin. What investigations would you consider? Answer: Serum barbiturate, benzodiazepine, salicylate, and paracetamol levels. Blood glucose, liver and renal function tests, full blood count, C-reactive protein, erythrocyte sedimentation rate, serum calcium, and thyroid function tests. Coma blisters are most commonly associated with barbiturate and benzodiazepine overdose but may be seen in association with other pharmacological agents, in carbon monoxide poisoning or in association with coma following intracerebral events. The cause is obscure but they are thought to be partly due to tissue fluid accumulation related to immobility and to be partly due to skin hypoxia. Common sites are the buttocks, thigh, loins, and shins.