[Cutaneous presentation of digestive tract disorders and liver disease]

A variety of skin conditions may be important diagnostic indicators for disorders of the digestive tract and liver. In inflammatory bowel diseases, the most common cutaneous manifestations are erythema nodosum and pyoderma gangrenosum. Autoimmune liver diseases are often associated with cutaneous manifestations such as hidradenitis suppurativa, vitiligo, psoriasis and alopecia areata. Lichen planus or porphyria cutanea tarda can also be induced by infectious hepatitis. Enteral malabsorption can lead to deficiencies and characteristic skin changes, such as celiac disease, acrodermatitis enteropathica, pellagra and scurvy. In addition, cutaneous sequelae, including various exanthems and adverse reactions, from drug treatment of intestinal and liver diseases are possible. Likewise, so-called paradoxical reactions in which new and previously absent skin conditions (e.g. psoriasis) may also develop, especially following treatment with biological products. Thus, gastroenterologists should recognize and diagnose cutaneous changes that are new or evolving in patients with intestinal and liver diseases in order to initiate appropriate therapy.