MRCP2-0997

MRCP2-0997

A 35-year-old woman of Indian origin is started on carbamazepine for generalized tonic-clonic seizures. She presents to the Emergency Department (ED) a few days later complaining of symptoms of lower respiratory tract infection (RTI), and severe blistering affecting her mouth and lips.
During examination, her temperature is 38.5°C. Her blood pressure (BP) is 120/80 mmHg, while her pulse is 85 beats per minute (bpm) and regular. You confirm a number of blisters within the oropharynx. She has a number of target lesions over the surface of her body, some of which have blistered with a necrotic center. In certain areas, the lesions have become confluent, with wider areas of skin loss.
Investigations reveal the following:
Haemoglobin (Hb) 140 g/l 120–160 g/l
White cell count (WCC) 12.5 × 109/l 4.0–11.0 × 109/l
Platelets (PLT) 180 × 109/l 150–400 × 109/l
Sodium (Na+) 138 mmol/l 135–145 mmol/l
Potassium (K+) 3.8 mmol/l 3.5–5.0 mmol/l
Creatinine (Cr) 100 µmol/l 50–120 µmol/l
Glucose 6.0 mmol/l 3.9–7.1 mmol/l
Erythrocyte sedimentation rate (ESR) 70 mm/hour 1–20 mm/hour

What is the most probable diagnosis?