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DR13.1 | Autoimmune Vesiculobullous Disorder Diagnosis — SDL Guide (Part 3)

Self-Assessment: Vesiculobullous Disorder Diagnosis

Vesiculobullous Disorder Diagnosis

Use the following structured reasoning to consolidate the competency before you move on. The goal is not to memorise a table but to be able to walk from a bedside finding to a confident diagnosis and an appropriate next step. Work through each prompt deliberately, stating your reasoning aloud or in writing, and check yourself against the principle that the level of the epidermal split — intra-epidermal in pemphigus, sub-epidermal in bullous pemphigoid — drives every downstream feature, from blister character to Nikolsky's sign to the immunofluorescence pattern. If you find yourself uncertain on any item, return to the relevant section above rather than guessing, because reversing the cleavage plane is the single commonest and most dangerous error in this topic.

• Pattern recognition: For a patient with flaccid oral and skin erosions and a positive Nikolsky's sign, state the diagnosis, the split level, the target antigen, and the expected DIF pattern.
• Sign interpretation: Explain in one sentence why Nikolsky's sign is positive in pemphigus vulgaris but negative in bullous pemphigoid.
• Investigation choice: A patient has tense bullae and a negative Nikolsky's sign. List, in order, the investigations you would request and the result you expect from each.
• Safe practice: Name the complication that is the leading cause of death in extensive pemphigus and one step you would take to reduce that risk before referral.