Anorexia nervosa (AN) is a significant cause of morbidity and mortality among adolescent females and young women. AN is associated with severe medical and psychological consequences, including death, osteoporosis, growth delay, and developmental delay. Skin signs are almost always detectable in severe AN and awareness of them may help in the early diagnosis of hidden AN. Skin signs are the expression of the medical consequences of starvation, vomiting, abuse of drugs, such as laxatives and diuretics, and of the psychiatric morbidity. They include xerosis, lanugo-like body hair, telogen effluvium, carotenoderma, acne, hyperpigmentation, seborrhoeic dermatitis, acrocyanosis, perniosis, petechiae, livedo reticularis, interdigital intertrigo, paronychia, acquired striae distensae, acral coldness.
The most characteristic cutaneous sign of vomiting is Russell's sign (knuckle calluses). Symptoms due to laxative or diuretic abuse include adverse reactions by drugs. Symptoms due to psychiatric morbidity (artefacta) include the consequences of self-induced trauma. The role of the dermatologist in the management of eating disorders is to make an early diagnosis of the "hidden"signs of eating disorders in patients who tend to minimize or deny their disorder.