Hard lumps behind the earlobe are commonly caused by local follicular infections or boils, sebaceous cysts, as follows: 1. Local follicular infections or boils: in addition to hard lumps and surface skin congestion, this condition is also painful to palpation when examined. You can use topical ointments such as Bactrim and erythromycin ointment to apply topically, and some serious infections can take oral antibiotics as appropriate to actively control the infection; 2. Sebaceous cysts: there is a certain degree of activity when palpated, and the effect of topical medication is not good. Those who are diagnosed can only remove the cyst wall cleanly by surgery at a later stage to prevent recurrence, and attention should be paid to preventing infection after surgery.