Differential Diagnosis for Left Ankle Pain
Single Most Likely Diagnosis
- Peroneal Tendinopathy: This condition is characterized by inflammation or degeneration of the peroneal tendons, which run along the lateral aspect of the ankle and behind the lateral malleolus. The pain pattern described, radiating up the fibula, is consistent with peroneal tendinopathy. The absence of abnormalities on ultrasound and X-ray does not rule out this diagnosis, as tendinopathy can be difficult to detect with these imaging modalities.
Other Likely Diagnoses
- Lateral Ankle Impingement: This condition occurs when there is compression of the soft tissues (such as tendons and ligaments) between the lateral malleolus and the fibula, leading to pain and inflammation. The location of the pain and the absence of a history of injury make this a plausible diagnosis.
- Peroneal Tenosynovitis: Inflammation of the synovial sheath surrounding the peroneal tendons can cause pain and swelling along the lateral aspect of the ankle, consistent with the symptoms described.
- Fibular Stress Reaction or Stress Fracture: Although X-rays were normal, stress reactions or stress fractures can sometimes be missed on initial imaging. These conditions could cause pain radiating up the fibula.
Do Not Miss Diagnoses
- Osteoid Osteoma: A small, benign bone tumor that can cause severe pain, often worse at night and relieved by NSAIDs. It might not be visible on initial X-rays, and further imaging like an MRI or a bone scan might be necessary for diagnosis.
- Erythromelalgia: A disorder characterized by burning pain, heat, and redness in the hands and feet. Although less common, it could present with pain localized to the ankle area.
- Complex Regional Pain Syndrome (CRPS): A condition characterized by chronic pain, inflammation, and hypersensitivity following an injury or trauma. The absence of a reported injury does not rule out CRPS, as it can sometimes occur without a clear precipitant.
Rare Diagnoses
- Fibular Osteonecrosis: A rare condition where a portion of the fibula bone dies due to lack of blood supply, potentially causing pain along the fibula.
- Intraosseous Ganglion Cyst of the Fibula: A benign cystic lesion within the bone that can cause pain and might not be visible on initial X-rays.
- Peripheral Nerve Entrapment: Entrapment of the peroneal nerve or its branches can cause pain and other symptoms along the lateral aspect of the ankle and leg.