What is the diagnosis for a patient with an MRI showing bone marrow edema of the distal fibula, a linear region of low signal extending from the physis (growth plate) distally, and no evidence of ligamentous injury, suggesting an undisplaced fracture involving the lateral malleolus with a possible Salter-Harris type 1 component?

Differential Diagnosis

• Single most likely diagnosis
  • Undisplaced Salter-Harris type I fracture of the distal fibula: This diagnosis is the most likely due to the presence of bone marrow edema of the distal fibula, a linear region of low signal extending from the physis distally, and minimal bone marrow edema superior to the physis without widening of the physeal plate.
• Other Likely diagnoses
  • Undisplaced Salter-Harris type II fracture of the distal fibula: Although the physeal plate is not widened, the presence of bone marrow edema superior to the physis could suggest a type II fracture.
  • Stress fracture of the distal fibula: The presence of bone marrow edema without a clear fracture line could indicate a stress fracture.
  • Traumatic injury to the distal fibula: The presence of bone marrow edema and a linear region of low signal could be indicative of a traumatic injury, such as a contusion or a small, undisplaced fracture.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Osteomyelitis: Although unlikely, osteomyelitis could present with bone marrow edema and should be considered, especially if there are signs of infection or systemic illness.
  • Malignant bone tumor: A malignant bone tumor, such as osteosarcoma or Ewing's sarcoma, could present with bone marrow edema and should be considered, especially if there are signs of systemic illness or a mass is present.
  • Pathologic fracture: A pathologic fracture due to a underlying bone lesion, such as a cyst or tumor, could present with bone marrow edema and should be considered, especially if there are signs of systemic illness or a mass is present.
• Rare diagnoses
  • Fibular aplasia or hypoucheroucher: A rare congenital condition where the fibula is absent or underdeveloped, which could present with abnormal bone marrow signal.
  • Fibrous dysimiter: A rare bone disorder that could present with bone marrow edema and abnormal bone signal.
  • Langerhans cell histiocytosis: A rare condition that could present with bone marrow edema and abnormal bone signal.