How is bullous pemphigoid (BP) diagnosed?

Updated: Oct 14, 2020
  • Author: Lawrence S Chan, MD; Chief Editor: Dirk M Elston, MD  more...
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Answer

To establish a diagnosis of bullous pemphigoid, the following tests should be performed:

  • Histopathologic analysis: From the edge of a blister; the histopathologic examination demonstrates a subepidermal blister; the inflammatory infiltrate is typically polymorphous, with an eosinophil predominance; mast cells and basophils may be prominent early in the disease course

  • Direct immunofluorescence (DIF) studies: Performed on normal-appearing, perilesional skin (see the image below), [2] or nonbullous urticarial skin; significant false-negative rate if skin biopsy is taken from skin of the legs [3]

  • Direct immunofluorescence study performed on a per Direct immunofluorescence study performed on a perilesional skin biopsy specimen from a patient with bullous pemphigoid detects a linear band of immunoglobulin G deposit along the dermoepidermal junction.
  • Indirect immunofluorescence (IDIF) studies: Performed on the patient’s serum, if the DIF result is positive (see the image below)

    Indirect immunofluorescence study performed on sal Indirect immunofluorescence study performed on salt-split normal human skin substrate with the serum from a patient with bullous pemphigoid detects immunoglobulin G class circulating autoantibodies that bind to the epidermal (roof) side of the skin basement membrane.

DIF tests in patients with bullous pemphigoid usually demonstrate immunoglobulin G (IgG) and complement C3 deposition in a linear band at the dermal-epidermal junction, with IgG in salt-split skin found on the blister roof (epidermal side of split skin).

IDIF studies document the presence of circulating IgG autoantibodies in the patient's serum that target the skin basement membrane component. Seventy percent of patients with bullous pemphigoid have circulating autoantibodies that bind to split skin.

See Workup for more detail.


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