Table 1.

Comparison of aetiology, triggers, pathology of GT and psoriasis. Current state of knowledge.

	Geographic Tongue	Psoriasis
Aetiology	Unknown, likely inflammatory and/or autoimmune?	Autoimmune
Triggers	Food, allergy, stress nutritional deficiencies, hormonal disturbances, gluten intolerance, oral microbiota?	Infections, skin injuries, cold, stress/psychological factors?
Pathophysiology	Atrophy of filiform papillae (depapillation, loss of epithelium), intense aggregation of neutrophiles in epithelium	Epidermal hyperproliferation, parkeratosis, increased epidermal the epidermal cell turnover rate
Pathological pathways	Neutrophiles, inflammatory mediators	Pro-inflammatory cytokines, with a dominant IL-23 and Th17 axis