Helicobacter pylori and skin disorders: a comprehensive review of the available literature.

Helicobacter pylori is a Gram-negative bacterium identified for the first time about 30 years ago and commonly considered as the main pathogenic factor of gastritis and peptic ulcer. Since then, it was found to be associated with several gastrointestinal and extra-gastrointestinal diseases. Helicobacter pylori is also associated with many skin disorders including, but not limited to, chronic urticaria, rosacea, lichen planus, atopic dermatitis, psoriasis, pemphigus vulgaris, vitiligo, primary cutaneous MALT-type lymphoma, sublamina densa-type linear IgA bullous dermatosis, primary cutaneous marginal zone B-cell lymphomas and cutaneous T-cell pseudolymphoma. Literature up to September 2020 shows that clear evidence exists only for some of the mentioned associations, while in the majority of cases, data appear contrasting. The aim of this review is to summarize the available studies on the topic and draw possible conclusions. Further clinical and laboratory studies are needed to assess the real plausibility and relevance of these associations, as well as the possible role of Helicobacter pylori with the underlying pathogenic mechanisms.