A hard lump on the ankle may be common warts, dermatofibroma, erythema nodosum and other diseases. 1. common warts: this disease is caused by the human papilloma virus, when the skin mucous membrane breaks, it is easy to be infected, the common high-risk groups are immunocompromised, malignant lymphoma patients. Common warts can occur in any part of the body, and solid pimples will appear locally, so some patients have a hard lump on their ankle. 2. Dermatofibroma: the cause of this disease is not clear, it may occur naturally, or it may be caused by trauma and insect bites. The main symptom is the presence of firm nodules at the skin lesions, brownish red or yellowish brown in color, which can be manifested as a hard lump on the ankle. 3. Erythema nodosum: studies have shown that the occurrence of this disease may be related to hemolytic streptococcus or viruses, chlamydia, fungi and other pathogenic microbial infections, and secondly, it may also be secondary to inflammatory bowel disease, autoimmune diseases, malignant tumors and other systemic diseases, the patient’s ankles can be present in the red nodules, which may be hard bumps. There are many causes of hard lumps on the ankles, so it is necessary to go to the hospital, complete the relevant examinations, identify the specific causes, and then standardize the treatment under the guidance of the doctor.