Association between geographic tongue and psoriasis: A systematic review and meta-analyses

Geographic tongue (GT) has been described as a predictor of psoriasis. The objective of this study was to analyse the prevalence of GT in psoriatic and non-psoriatic patients. For this purpose, we conducted a systematic review and meta-analysis. A literature search was performed on PubMed, Embase, Web of Science and the Cochrane Database of Systematic Reviews. The search and selection process was performed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) criteria. Only case-control studies were selected, and the prevalence of GT in both groups was compared. Eleven articles met the inclusion criteria, and the frequency of GT was statistically associated with psoriasis in ten studies. The pooled odds ratio (OR) was 3.53 (95% confidence interval [CI] 2.56-4.86). There were no significant differences between the presence of GT and the clinical form. However, the Psoriasis Area and Severity Index (PASI) score was statistically higher in patients affected by GT in three of four studies. Psoriatic patients with GT also exhibited less improvement in the PASI score after treatment. One study found an association between GT and a negative impact on patients' quality of life. Nevertheless, age, gender, toxic habits, psoriasis onset and duration of the disease were not clearly associated. The results support the concept of GT as a manifestation of psoriasis. Future research should focus on the repercussions of GT in psoriatic patients, due to the negative consequences on severity and treatment response.