Toxic epidermal necrolysis — an investigation to dye for?

A 44-year-old woman presented to the emergency department with a 3-day history of a progressive rash, fever, malaise and mucosal ulceration. She met the diagnosis of toxic epidermal necrolysis (TEN) based on the following criteria: bullae and desquamation affecting about 84% of the body surface (Box 1 and Box 2), buccal and vaginal ulceration, a positive Nikolsky sign (this is a useful sign in bullous skin diseases and can be demonstrated by rubbing the skin surface, which will blister within a few minutes if the sign is positive), fever, tachycardia and mild hypotension. She also had abnormal results of liver function tests: bilirubin level, 69 μmol/L (reference interval [RI], < 20 μmol/L); alkaline phosphatase level, 180 U/L (RI, 25–100 U/L); γ-glutamyl transferase level, 499 U/L (RI, < 30 U/L); alanine aminotransferase level, 1730 U/L (RI, < 30 U/L); and aspartate aminotransferase level, 638 U/L (RI, < 30 U/L). She had a white cell count of 4.3 109/L (RI, 4.0–10.0 109/L) and a raised C-reactive protein level of 53.1 mg/L (RI, < 5 mg/L).