Background:Geographic stomatitis is an uncommon oral lesion that presents similar clinical, histopathological and genetic features as those of psoriasis. These findings suggest that this lesion may actually represent an oral manifestation of psoriasis. We report one case of geographic stomatitis and discuss a possible connection between this condition and psoriasis.Main observations:A 37-year-old woman presented with red patches, surrounded by a white border on the labial mucosa and a positive family history of psoriasis. Histopathological examination, immunohistochemical analysis with antibodies against CD4, CD8, CD20, CD68, CD31, and Ki-67 and HLA-A*, -B*, -C*, -DRB1*, -DQA1* and -DQB1* genotyping were performed. Histopathological examination revealed parakeratosis, marked elongation of rete ridges with acanthosis and clubbing, exocytosis, Munro microabscesses, pustule of Kogoj, dilated tortuous vessels at the tip of dermal papillae, and predominant superficial and perivascular lymphocytic chronic inflammatory cell infiltrate. Immunohistochemistry analysis revealed a predominant T-cell subepithelial infiltrate. Based on the referred clinicopathological findings and in the absence of cutaneous lesions, the diagnosis of geographic stomatitiswas confirmed.Conclusions:This case and theoretical data indicate that geographic stomatitis may be an oral manifestation of psoriasis. Moreover, to improve our understanding, psoriatic patients should routinely undergo a detailed oral examination and patients with geographic stomatitis should routinely be submitted to a cutaneous routine examination.