IgA deposits in the oral mucosa of patients with dermatitis herpetiformis and linear IgA disease.

The oral mucosa of seven patients with dermatitis herpetiformis (DH) and one with linear IgA disease was studied. None of the patients with DH showed any macroscopic oral lesions, but direct immunofluorescence (IFL) examination of the buccal mucosa revealed granular IgA deposits in all patients. IgA deposits were found just below the basement membrane zone or slightly deeper in the connective tissue, i.e. a deposition pattern which is pathognomonic to DH. In three patients C3 deposits occurred in the same area as IgA. The patient with linear IgA disease had small white erythematous patches, nonspecific both clinically and histologically, on the palatal mucosa. However, oral IFL specimens showed heavy linear IgA deposits in the basement membrane zone, indicating that the oral mucosa is also involved in this rare disease. Buccal mucosal biopsy specimens were stained with four FITC-conjugated lectins (Ulex europaeus I, soybean, peanut and lentil). The lectin staining was similar in patients with DH and linear IgA disease and did not markedly differ from normal oral mucosa. Our results show that buccal IFL examination is a useful diagnostic aid in both DH and linear IgA disease.