A hard bump on the auricle may be caused by auricular pseudocysts, folliculitis, auricular boils, mosquito bites and other causes. 1. Auricular pseudocyst: often due to local sebaceous gland blockage to form pseudocysts, with the prolongation of the course of the disease, ooze water absorption, fiber mechanization can form a hard bump. 2. Folliculitis: the hair follicles in the auricle are infected by bacteria, which triggers an inflammatory reaction, resulting in a hard bulge accompanied by pain. 3. Auricular boils: boils on the auricle cause hard bumps that, if mature, can be painful and fluctuate when touched. 4. Mosquito bites: A mosquito bite on the auricle of the ear creates an allergic reaction and a hard lump. There are other possible causes for a hard bump on the auricle of the ear. It is recommended to consult a doctor to find out the cause of the problem and follow the doctor’s instructions for treatment.