A 32-year-old woman presents with extensive blistering, mucosal erosions, and fever 10 days after starting trimethoprim-sulfamethoxazole for a urinary tract infection. Skin biopsy shows full-thickness epidermal necrosis with subepidermal blister formation. On examination, 35% of her body surface area shows epidermal detachment. Which feature best distinguishes her condition from Stevens-Johnson Syndrome?