Abstract Background The sternum is considered an unusual tumor site, corresponding to 15% of all thoracic wall tumors. Primary sternal tumors are even rarer and most commonly malignant. We present the case of a young man who consulted with a painful sternal mass, which after its resection is confirmed to be a cavernous hemangioma. Case presentation A 39-year-old man, with unremarkable medical history besides a 2-year-long sternal pain, non-irradiated, which worsens over the last few months and is accompanied by the appearance of a sternal palpable mass. On physical exam, there was a bulging of the sternal manubrium, with no inflammatory changes. Thoracic CT scan shows an expansive and lytic lesion of the sternum, compromising the manubrium and extending to the third sternocostal joint, without intrathoracic compromise nor cleavage plane with mediastinal vascular structures. The patient is taken to resection of the mass and sternal reconstruction using prosthetic material and pectoral and fasciocutaneous muscular flaps. Histopathological findings: cavernous hemangioma with negative borders and no other malignant findings. Conclusions Sternal hemangiomas can cause defects in the bone structure and show an expansive growth, challenging the differentiation between a benign or malignant lesion. Therefore, they should be considered malignant until shown otherwise. Management involves radical surgery with curative purposes and posterior reconstruction to improve quality of life, as shown with our patient.