Diagnostic value and practicability of serration pattern analysis by direct immunofluorescence microscopy in pemphigoid diseases

In pemphigoid diseases, direct immunofluorescence can be used to differentiate 2 patterns of antibody deposition at the dermal-epidermal junction; u- and n-serrated pattern. The u-serrated pattern is found in epidermolysis bullosa acquisita, and n-serrated pattern in all other pemphigoid diseases. To determine the detection frequency of these serrated patterns and the optimal thickness of biopsy cryosections, 2 patient cohorts obtained form our routine autoimmune laboratory were analysed; a retrospective cohort (n = 226) and a prospective cohort (n = 156). In 76% (291/382) of biopsies, a pattern was recognized, of which 96% (278/291) and 4% (13/291) had an n- or u-serrated pattern, respectively. A u-serrated pattern was seen in all epidermolysis bullosa acquisita biopsies confirmed by serology. No antibodies against type VII collagen were detected in any of the sera from biopsies with nserrated pattern. No differences between the detection frequencies of serrated pattern were seen with respect to age, sex, biopsy site, or section thickness, while the detection frequency was higher in patients with serum anti-BP180 reactivity compared with those without. In conclusion, serrated pattern analysis using direct immunofluorescence has a high detection frequency and specificity for epidermolysis bullosa acquisita and will further facilitate the diagnosis of latter disorder.