Background Mucosal involvement is frequently seen in cutaneous lupus erythematosus (CLE) and systemic lupus erythematosus (SLE). There is no consensus regarding the prevalence, and a wide range of lesions has been reported. Its prognostic significance is currently unknown and a matter of controversy. Objective To classify oral lesions in lupus, evaluate their prevalence and assess their possible association with disease activity. Methods We conducted a descriptive study between 2016 and 2017. A total of 150 lupus patients were matched by sex, age and smoking status with 151 healthy individuals. All subjects underwent a careful evaluation of oral mucosa. On the same day of the clinical assessment, each patient underwent a peripheral venous blood and urine analysis. All patients underwent a full medical history, physical examination and a careful examination of the oral cavity. For each one, we obtained photographs of ten areas of the oral cavity. Two dermatologists of our group blindly recorded the presence and morphology of oral lesions. The disease activity of CLE patients was scored using the Revised Cutaneous Lupus Erythematosus Disease Area and Severity Index, and in SLE patients, activity was measured using the Systemic Lupus Erythematosus Disease Activity Index. Results In CLE patients, there was a statistically significant correlation between higher cutaneous disease activity and the following oral findings: discoid plaques, cobblestone and red/brown‐pigmented macules. In patients with CLE, red macules on jugal mucosa were statistically associated with anaemia and positive antinuclear antibodies titres; additionally, the presence of gingivitis was related to systemic inflammation. In SLE patients, gingival telangiectases were statistically significantly associated with leucopenia, hypocomplementemia and systemic inflammation. Limitations Biopsies on mucosal lesions were not performed. Conclusion Some specific oral lesions correlate with disease activity in CLE and SLE.

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Background Dermatomyositis (DM) patients are frequently misdiagnosed as having lupus erythematosus. There are few tools to differentiate between these diseases.Objective To compare oral findings between patients with systemic lupus erythematosus (SLE), cutaneous lupus erythematosus (CLE), and DM patients to explore new clinical tools that allow differentiating between these conditions.Methods We conducted an observational, transversal, and analytical study between 2016 and 2021. One hundred sixty-seven patients were included (77 SLE, 56 CLE, and 34 DM). All patients who presented with more than one of these diseases simultaneously were excluded. All patients had a clinical evaluation of the oral cavity. We obtained photographs of the tongue, hard and soft palate, upper and lower gingiva, and jugal mucosa. Three dermatologists, blinded to the diagnosis of the diseases studied, registered the presence of the lesions of interest.Results The presence of brown pigmentation in the gingiva, whitish streaks in the jugal mucosa, palatal cobblestones, and gingival cobblestones were associated with SLE and CLE when compared with DM patients. Palatal cobblestones were present exclusively in patients with SLE and CLE. Gingival telangiectasias were associated with DM when compared with SLE, and palatal telangiectasias and well-defined palatal lesions were associated with DM when compared with SLE and CLE. Most DM patients presented palatal telangiectasias (94.12%), while this finding in SLE and CLE patients was infrequent (7.79% and 5.36%, respectively).Conclusion Oral findings can help differentiate between SLE, CLE, and DM patients when there is a diagnostic dilemma between these conditions.