<s>[INST] I have a small and hard lump about the size and feel of a pebble or frozen pea under the front of my chin and immediately behind the bone at the point of my chin. There is another identical lump also under my skin just resting above my left jaw bone. Any ideas what it could be? [/INST] Hi Dear, Welcome to Chat Doctor. Understanding your concern. As per your query hard lumps on chin and jaw bone could be due to blockage of salivary gland ducts such as sub-mandibular duct. It could be due to sebaceous cyst or some other cysts like bronchial cyst or lymphatic cysts. Lipoma and lymph node swelling is another major cause for your condition. Treatment depends on proper diagnosis. I would suggest you to visit oral physician once and get it examined. Go for an FNAC /biopsy and ultrasound of the lumps for confirmation and to relieve your concerns. Take proper course of antibiotic for infection regression. Hope your concern has been resolved. Get Well Soon. Best Wishes, </s>