Itchy bumps on the knuckles can be caused by eczema, or by contact dermatitis, or by warts. 1. Eczema: is a variety of internal and external factors caused by the superficial dermis and epidermal inflammation, the disease can lead to the patient appeared on the knuckles pimples very itchy symptoms. 2. Contact dermatitis: a disease caused by contact with metals, gasoline, cosmetics, hair dyes and other substances, which can also lead to symptoms of itchy bumps on the knuckles. 3. Warts: are due to infection with human papilloma virus (HPV) and the formation of benign superfluous organisms, the disease can also lead to patients with small bumps on the knuckles very itchy symptoms. In addition to the above diseases, other factors can also lead to the symptoms of itchy bumps on the knuckles, it is recommended to consult a doctor in time to find out the cause, and follow the doctor’s instructions for treatment.