Case Presentation: A 58-year-old male with previously treated non-Hodgkin lymphoma and multiple myeloma was admitted with 3 weeks of progressively worsening mucocutaneous blisters. The initial pruritic blister was located on the right arm and progressively spread to include his extremities, chest, back, and groin (covering 60% TBSA), with mucosal involvement, and an inability to tolerate [...]