Hi Thanks for posting your query on HCM. I appreciate your concern for the painful lump at the bottom of sternum. Incomplete data like age, does the lump bulge during coughing, sneezing or straining during defecation? I have gone through your problem diligently, I am of the opinion you have some sort of hernia referred to as epigastric hernia. It is due to a small bit of fat that bulges through a weakness in the upper abdominal muscles between the umbilicus and the sternum. Commonly seen in people during 20-50 yrs of ages. Most of the hernias do not cause any symptoms and hence need not to be operated on. Hernias that cause symptoms or that become larger should be repaired by a surgeon. Since in your case the hernia becomes painful when it is pressed, hence I would advice you to kindly consult a surgeon for proper physical examination. Hope this answers your query. wishing you good health. Regards.