Hard lumps on the front of children’s calves may be caused by epidermoid cysts, dermatofibroma, folliculitis and other causes. 1. Epidermoid cysts: Epidermoid cysts are a kind of benign skin tumors, which are cysts containing keratin in the dermis and are common skin cysts. Typical symptom is that the lesion is a dome-shaped swelling elevated above the skin, hard, elastic and movable. 2. Dermatofibroma: This disease may be a reactive proliferation of fibroblasts triggered by a tiny skin injury rather than a true tumor. Typical skin lesions are slow-growing round or ovoid solid nodules with smooth or rough surface, often single, occasionally multiple, with a diameter of several millimeters to 1cm, with colors ranging from brownish red, yellowish brown to blackish brown, and usually with no self-conscious symptoms. 3. Folliculitis: Folliculitis is a kind of hair follicle inflammation, mainly caused by Staphylococcus aureus infection of the hair follicle, the clinical manifestations of follicular papules, and then the formation of small pustules, in the recovery of folliculitis will form a hard lump. It is recommended to go to the hospital for examination, and the doctor will give judgment according to the clinical symptoms, and clarify the cause of the disease and timely symptomatic treatment.