Immunofluorescence serration pattern analysis as a diagnostic criterion in antilaminin-332 mucous membrane pemphigoid: immunopathological findings and clinical experience in 10 Dutch patients

Background Antilaminin-332 mucous membrane pemphigoid (anti-LN-332 MMP) is a chronic subepidermal blistering disease characterized by IgG anti-epidermal basement membrane zone (BMZ) autoantibodies against laminin-332 (LN-332). Patients with anti-LN-332 MMP have an increased relative risk of malignancy. Laboratory techniques that are difficult to obtain are needed for diagnosis of anti-LN-332 MMP.

Objectives To incorporate direct immunofluorescence (DIF) serration pattern analysis of IgG depositions in the diagnostic criteria of anti-LN-332 MMP.

Methods Patients who met our revised inclusion criteria for anti-LN-332 MMP were selected from our biobank over the period 1997-2009. Inclusion criteria were clinical symptoms, DIF serration pattern analysis, indirect immunofluorescence (IIF) on salt-split skin, and antigen-specificity analysis of the serum including immunoblotting and/or immunoprecipitation and/or enzyme-linked immunosorbent assay (ELISA) against native LN-332.

Results Ten patients met the inclusion criteria. A malignancy was found in two patients (20%). In all patients in whom it was performed (n = 9), DIF showed linear IgG deposition along the BMZ in an n-serrated pattern. Nine sera reacted by salt-split skin analysis and bound to the dermal side of the split skin. ELISA against native LN-332 was positive in 78% of the tested sera.

Conclusions Anti-LN-332 MMP can clinically resemble other forms of pemphigoid. Although state-of-the-art laboratory diagnostics are necessary for definite diagnosis, the combination of simple DIF serration pattern and IIF salt-split skin analysis will exclude other forms of MMP and epidermolysis bullosa acquisita from the differential diagnosis. Because of the increased risk for malignancy patients should be thoroughly oncologically screened.