Differential Diagnosis for Adolescent Patient with Unusual Painless Swelling of the Lower Ribs

Single Most Likely Diagnosis

• Costochondritis: This condition, also known as Tietze's syndrome, is characterized by inflammation of the cartilage that connects the ribs to the breastbone (sternum). It can cause swelling and tenderness, typically on one side of the chest, and is often seen in adolescents. The painless nature of the swelling, although less common, can sometimes be a presentation of costochondritis, especially if the inflammation is mild.

Other Likely Diagnoses

• Musculoskeletal Injury: Trauma to the chest wall can cause swelling and pain, but in some cases, the pain may be minimal or absent, especially if the injury is not severe. This could include strains or bruises to the muscles or ligaments around the ribs.
• Rib Tumors or Cysts: Benign tumors such as osteochondromas or unicameral bone cysts can cause swelling of the ribs. These conditions are generally painless unless they cause a fracture or impinge on surrounding structures.

Do Not Miss Diagnoses

• Ewing's Sarcoma: A rare type of cancer that typically occurs in bones or in the soft tissue around the bones. It can cause pain, swelling, and tenderness, but in early stages, it might be painless. Early diagnosis is crucial for effective treatment.
• Osteomyelitis: An infection of the bone that can cause pain, swelling, and redness. In some cases, especially in the early stages, the pain might be minimal or absent, making it a "do not miss" diagnosis due to its potential for serious complications if not treated promptly.
• Lymphoma: Although less common, lymphoma can cause swelling in the chest area, including the lower ribs, if lymph nodes in that region are involved. It's a critical diagnosis not to miss due to its implications for treatment and prognosis.

Rare Diagnoses

• Multiple Hereditary Exostoses (MHE): A rare genetic disorder characterized by the growth of multiple bony spurs or osteochondromas. These growths can cause swelling and, in some cases, might be painless.
• Fibrous Dysplasia: A condition where normal bone and marrow are replaced with fibrous tissue, leading to the formation of weakened and sometimes deformed bones. It can cause swelling and might be painless unless there is a fracture or other complication.
• Chondrosarcoma: A type of cancer that begins in the cartilage around the bones. It is rare and can cause painless swelling in the early stages, making it a diagnosis to consider in the differential, especially if other signs or risk factors are present.