A bunch of rice-like bumps behind the ears, considering pathological factors such as allergies, keratosis pilaris, eczema, molluscum contagiosum, flat warts and other causes. 1. Skin allergy: If the skin behind the ear is stimulated by skin care products, hair dyes, air dust and other stimuli causing local allergies, eczema can appear, manifested as a bunch of small bumps behind the ear, can also be accompanied by itching and other symptoms. 2. Keratosis pilaris: mostly related to heredity, may also be the body intake, utilization and metabolism of vitamin A disorders caused by the ear when the ear can cause a lot of rice-like pimples. 3. Molluscum contagiosum: mostly related to viral infection, obesity, ultraviolet radiation and other factors, lesions involving the ear, can be manifested as a lot of rice-like pimples behind the ear. 4. flat warts: when the skin behind the ear is infected with human papilloma virus, it can cause the abnormal proliferation of local epithelial cells behind the ear, resulting in flat warts, which are mainly manifested as a lot of rice-like bumps behind the ear.