Differential Diagnosis for Distal Femur Lobulated Lesion

• Single most likely diagnosis
  • Giant Cell Tumor (GCT): This is a common tumor found in the distal femur, especially in skeletally mature individuals. The lobulated appearance is characteristic, and GCTs are known for their epiphyseal location, which fits with the distal femur presentation.
• Other Likely diagnoses
  • Chondroblastoma: Although less common than GCT, chondroblastoma is another epiphyseal tumor that can present with a lobulated appearance. It tends to occur in younger patients and can have a similar location.
  • Aneurysmal Bone Cyst (ABC): ABCs can occur in the distal femur and may present with a lobulated or expansile appearance. They are typically seen in younger patients and can be associated with other lesions.
  • Osteosarcoma: While not typically lobulated, some variants of osteosarcoma, especially the telangiectatic type, can have a cystic or lobulated appearance. Given the potential for malignancy, it's an important consideration.
• Do Not Miss diagnoses
  • Metastasis: Metastatic lesions to the bone can have a variety of appearances, including lobulated. Given the potential for serious underlying disease, missing a diagnosis of metastasis could be catastrophic.
  • Infection (e.g., Osteomyelitis): Chronic osteomyelitis can result in a variety of bone changes, including cystic or lobulated lesions. Failing to diagnose and treat infection can lead to significant morbidity.
• Rare diagnoses
  • Chordoma: While rare, chordomas can occur in the distal femur and may have a lobulated appearance. They are typically seen in older adults and can be slow-growing.
  • Hemangioma of Bone: Bone hemangiomas are rare and can have a variety of appearances, including a lobulated or cystic pattern. They are usually benign but can cause symptoms due to their location or expansion.