A hard lump under the foreskin after circumcision may be related to keloid hyperplasia, inflammatory lump, thread knot lump and other reasons. 1. Keloid hyperplasia: Fibrous hyperplasia occurs at the incision of circumcision surgery, and keloid can be formed, which is a normal phenomenon of tissue repair, and generally does not require special treatment. 2. Inflammatory lumps: If there is a localized infection after the circumcision surgery that causes an inflammatory reaction, an inflammatory lump may appear, which is manifested as a hard lump under the foreskin. 3. Thread knot lumps: if after circumcision surgery in the wound knot thread knot, can be caused by the phenomenon of hard lumps under the foreskin. It is recommended that after circumcision there is a hard lump under the foreskin timely consultation, clear reasons, if you need treatment, should be standardized treatment under the guidance of the doctor.