Abstract Background: Psoriasis is a skin-articular disease with unclear etiopathogenesis. It has been suggested that the disease is immune-mediated by T-lymphocytes, predominantly Th17 cells. Similar to psoriasis, geographic tongue is an inflammatory disease with participation of Th17 cells and direct correlation with psoriasis. Objective: To investigate and compare the inflammatory responses and the Th17 pathway in psoriasis and geographic tongue. Methods: This was a cross-sectional study with 46 participants that were categorized into three groups: (A) patients with psoriasis vulgaris; (B) patients with geographic tongue and psoriasis; (C) patients with geographic tongue without psoriasis. All patients underwent physical examination, and a skin and oral biopsy for histopathological examination and immunohistochemical analysis with anti-IL6, anti-IL17, and anti-IL23 antibodies. Results: Histological analysis of all lesions showed mononuclear inflammatory infiltrate. However, moderate intensity was prevalent for the patients with geographic tongue and psoriasis and geographic tongue groups. Immunopositivity for the antibodies anti-IL6, anti-IL17, and anti-IL23 revealed cytoplasmic staining, mainly basal and parabasal, in both psoriasis and geographic tongue. Regarding IL-6, in patients with geographic tongue and psoriasis cases the staining was stronger than in patients with geographic tongue without psoriasis cases. IL-17 evidenced more pronounced and extensive staining when compared to the other analyzed interleukins. IL-23 presented similar immunopositivity for both geographic tongue and psoriasis, demonstrating that the neutrophils recruited into the epithelium were stained. Study limitation: This study was limited by the number of cases. Conclusion: The inflammatory process and immunostaining of IL-6, IL-17, and IL-23 were similar in geographic tongue and psoriasis, suggesting the existence of a type of geographic tongue that represents an oral manifestation of psoriasis.

Abstract: Geographic tongue is a chronic, inflammatory, and immune-mediated oral lesion of unknown etiology. It is characterized by serpiginous white areas around the atrophic mucosa, which alternation between activity, remission and reactivation at various locations gave the names benign migratory glossitis and wandering rash of the tongue. Psoriasis is a chronic inflammatory disease with frequent cutaneous involvement and an immunogenetic basis of great importance in clinical practice. The association between geographic tongue and psoriasis has been demonstrated in various studies, based on observation of its fundamental lesions, microscopic similarity between the two conditions and the presence of a common genetic marker, human leukocyte antigen (HLA) HLA-C*06. The difficulty however in accepting the diagnosis of geographic tongue as oral psoriasis is the fact that not all patients with geographic tongue present psoriasis. Some authors believe that the prevalence of geographic tongue would be much greater if psoriatic patients underwent thorough oral examination. This study aimed to develop a literature review performed between 1980 and 2014, in which consultation of theses, dissertations and selected scientific articles were conducted through search in Scielo and Bireme databases, from Medline and Lilacs sources, relating the common characteristics between geographic tongue and psoriasis. We observed that the frequency of oral lesions is relatively common, but to establish a correct diagnosis of oral psoriasis, immunohistochemical and genetic histopathological analyzes are necessary, thus highlighting the importance of oral examination in psoriatic patients and cutaneous examination in patients with geographic tongue.