This fact is from Vesiculobullous Diseases in Oral Medicine & Radiology. It is a commonly tested concept in NEET MDS examinations. Understanding this fact is crucial for answering MCQs correctly.
Pemphigoid = SUBepithelial linear DIF
Erythema multiforme = target lesions iris lesions = drug hypersensitivity
Stevens-Johnson syndrome = severe mucocutaneous EM
Dermatitis herpetiformis = celiac disease associated
Epidermolysis bullosa = genetic blistering = absent collagen VII.