Erythema pigmentosum is known as follicular erythema pigmentosum of the face and neck. The cause of the disease is still unclear, and it may be related to heredity, vitamin A deficiency and other factors. 1. Genetic factors: erythema pigmentosum is a hereditary disease, which may be caused by autosomal recessive inheritance or spontaneous mutation. 2. Vitamin A deficiency: when the body is deficient in vitamin A, it may lead to dry skin and keratinization of hair follicles, which may induce erythema pigmentosum. When suffering from erythema nigricans, you can go to the hospital in time, under the guidance of physicians for related treatment.