Laboratory Tests for Diagnosing Bullous Pemphigoid

Essential Diagnostic Tests

The British Journal of Dermatology recommends that biopsy specimen should be obtained from perilesional skin (not from the blister itself) for diagnosing bullous pemphigoid 1, 3
Positive finding in direct immunofluorescence microscopy: Linear (n-serrated) deposits of IgG and/or C3 along the dermoepidermal junction, sometimes IgA and IgE may show similar pattern of deposition 4
Specimens for histopathology should be taken from early bullae arising on erythematous skin and placed in formalin solution, with typical findings including subepidermal bullae containing eosinophils and/or neutrophils 1, 2, 4

Detection of circulating IgG antibasement membrane autoantibodies using NaCl-separated normal human skin (salt-split skin technique) is recommended, with positive finding: IgG antibodies binding to the epidermal side (sometimes both epidermal and dermal) of the split 1, 4
Detection of anti-BP180 (BPAG2/type XVII collagen) IgG autoantibodies and anti-BP230 (BPAG1-e) IgG autoantibodies by ELISA is recommended, with anti-BP180 ELISA values >27 U/mL indicating increased risk of relapse 1, 4, 5

Clinical assessment using validated clinical criteria for BP, with diagnosis highly likely in patients with positive DIF when three of four clinical characteristics are present (age >70 years, absence of atrophic scars, absence of mucosal involvement, absence of predominant bullous lesions on neck and head) 1, 2
First-line laboratory tests include DIF of perilesional skin and histopathology of early intact bulla 1, 2, 3

Regular monitoring of complete blood count, erythrocyte sedimentation rate, C-reactive protein, creatinine, blood electrolytes, fasting glucose, liver function tests, and serum albumin is recommended 6
Regular monitoring of anti-BP180 IgG by ELISA can help assess disease activity and predict relapse 5