Deposits of immunoglobulins, complement, and fibrinogen in oral lupus erythematosus, lichen planus, and leukoplakia.

Direct immunofluorescent staining (IF) for detection of deposits of IgG, IgM, IgA, complement C3, and fibrinogen at the basement membrane zone has been performed on a total of 279 biopsy specimens from oral lesions and clinically normal oral mucosa from the following groups of patients: fourty-five discoid lupus erythematosus (DLE), including sixteen patients without skin lesions, seven systemic lupus erythematosus (SLE); fourty-five lichen planus (LP); thirty leukoplakia (Leuk.); twenty patients with uncertain diagnosis, termed DLE? LP?; and twenty-three healthy persons. Deposits of immunoglobulins (lg) occurred in 73 percent of oral lesions in DLE and in 100 percent of the oral lesions in SLE, whereas lg deposits occurred in 3 to 30 percent in the other groups, the differences being significant (P less than 0.05). It is concluded that lg deposits are a characteristic feature of oral lesions of DLE and SLE and only rarely occur in oral lesions of LP and Leuk., which are the most important differential diagnoses. A direct immunofluorescence test on oral lesions suspected to be LE should be regarded as positive only if lg deposits are present, since C3 occurs frequently in oral lesions other than LE. Consideration can be given to the inclusion of lg deposits in the diagnostic criteria for oral LE lesions.