Large hard bumps on the chin may be related to acne, keloids, dermatofibromas, pigmented nevi, and other factors. 1. Acne: Acne may occur on the face and is associated with increased sebaceous gland secretion and blockage of follicular openings. Acne that is harder may be the result of an inflammatory reaction, such as inflammation leading to inflammatory edema, which may lead to hardening of the pimples. 2. Keloid, dermatofibroma: keloid may be related to heredity, keloid hard texture; dermatofibroma, if occurring in the chin area, can also lead to local hard pimples. 3. Pigmented nevus: pigmented nevus is a benign tumor of melanocytes, which can occur in the chin area, leading to the local appearance of yellow-brown, black, round, hardness similar to the skin swelling. It is recommended not to use medicine blindly, go to the hospital for examination and find the cause for active treatment.