MSRA-0363
A 45-year-old man presents to the Emergency Department with a rash and feeling generally unwell. He has a history of epilepsy and recently started taking phenytoin three weeks ago. He developed mouth ulcers, malaise, and a cough about a week ago. Two days ago, he developed a widespread red rash that has now formed large fluid-filled blisters, covering approximately 30% of his body area. The lesions separate when slight pressure is applied. Upon examination, his temperature is 38.3ºC and pulse is 126/min. Blood results reveal:
Na+ 144 mmol/l
K+ 4.2 mmol/l
Bicarbonate 19 mmol/l
Urea 13.4 mmol/l
Creatinine 121 µmol/l
What is the most likely diagnosis?