Medical Imaging Analysis Report

1. Imaging Findings

Based on ultrasound and MRI images, the following observations are made:

• A well-defined cystic lesion is seen near the right fibular head, with signal characteristics consistent with a cystic structure (low signal on T1-weighted images, high signal on T2/STIR-weighted images).
• Ultrasound shows the lesion is anechoic or hypoechoic internally, with a relatively regular boundary. Color Doppler reveals no obvious abnormal blood flow signals, suggesting a high likelihood of a cystic lesion.
• MRI indicates this lesion is adjacent to structures near the fibular head, with localized soft tissue swelling. There is no clear bone destruction noted in the surrounding area.
• Clinically, the patient complains of sensory disturbances over the lateral aspect of the right lower leg and dorsum of the foot, with reduced strength in dorsiflexion and eversion. These symptoms align with compression of the common peroneal nerve or its branches in that region.

2. Possible Diagnoses

Based on the patient’s symptoms (sensory disturbances, weakness in foot dorsiflexion) and imaging features (cystic lesion in the fibular head region), the following differential diagnoses are considered:

1. Ganglion Cyst around the Fibular Head (Joint/Tendon Sheath Cyst):
   Cysts commonly occur near joints or tendon sheaths and can cause local nerve compression. On imaging, they typically show low signal on T1 and high signal on T2, with anechoic or low-echo features on ultrasound and well-defined margins, matching the characteristics in this case.
2. Lipoma:
   Though commonly found in soft tissue, a lipoma on MRI usually appears with signals similar to subcutaneous fat and does not typically present as a clear cystic structure. If there is mixed fatty tissue, it might mimic a cystic lesion, but lipomas generally show high signal on T1, making them less likely given this case’s cystic appearance.
3. Schwannoma:
   Tumors may arise from peripheral nerve sheaths but often exhibit different T1/T2 characteristics compared to a simple fluid-filled cyst. Schwannomas also typically demonstrate more pronounced enhancement or solid components. The imaging in this case favors a cystic lesion, making schwannoma less probable.
4. Post-traumatic Localized Liquefied Hematoma/Mass:
   A hematoma resulting from trauma may evolve into a cystic structure. However, hematomas often present with septations or mixed echoes/signals, and the clinical history would typically include a clear progression after trauma. The ultrasound and MRI findings here strongly indicate a classic cystic lesion, making a typical hematoma less likely.

3. Final Diagnosis

Considering the patient’s age, clinical complaints (sensory deficits, muscle weakness), any relevant trauma history, and the ultrasound and MRI findings of a cystic lesion near the fibular head, the most likely diagnosis is:

“A ganglion (joint/tendon sheath) cyst near the fibular head causing compression of the common peroneal nerve.”

If further confirmation is needed, the following steps can be considered:

• Electrophysiological testing (EMG/NCV) of the common peroneal nerve to evaluate the extent and severity of nerve conduction impairment.
• Occasionally, aspiration or surgical exploration may be performed to confirm the nature of the cyst and decompress the nerve if necessary.

4. Treatment Plan and Rehabilitation Program

(1) Treatment Strategy:

• Conservative Management: If symptoms are mild and primarily sensory, short-term rest, immobilization, or symptomatic relief measures (e.g., local heat therapy, NSAIDs for pain and inflammation) may be tried. In cases with confirmed common peroneal nerve compression, close monitoring is required to watch for disease progression.
• Surgical Intervention:
  For patients with marked symptoms, progressive nerve damage, or severe compression confirmed by electrodiagnostic studies, surgical removal of the cyst and nerve decompression is often recommended. Surgery can prevent further nerve damage and help alleviate symptoms. Regular follow-up is advised postoperatively to monitor for cyst recurrence or nerve recovery.

(2) Rehabilitation and Exercise Prescription (FITT-VP Principle):

• Phase Goals:
  • Early phase: focus on pain relief, reducing swelling, and preventing muscle atrophy.
  • Intermediate phase: gradually restore joint mobility and muscle strength.
  • Late phase: enhance proprioception and functional training.
• Frequency (F):
  • Early phase: 1–2 daily sessions of low-intensity rehabilitation exercises (e.g., ankle pumps, toe grips).
  • Intermediate and later phases: gradually increase to 3–5 sessions per week, depending on surgical or conservative treatment progress.
• Intensity (I):
  • Start with light resistance, aiming for 10–15 repetitions that produce slight fatigue.
  • Increase load or resistance band intensity as muscle strength improves.
• Time (T):
  • Each rehabilitation session may last 20–30 minutes initially, extended to 45 minutes as tolerated.
  • Progress gradually and avoid excessive fatigue that could contribute to reinjury.
• Type (T):
  • Early phase: joint mobilization, strength exercises, and nerve gliding techniques.
  • Intermediate/late phase: introduce low-impact aerobic activities such as cycling or swimming; incorporate proprioceptive and balance training (e.g., single-leg stance, wobble board exercises).
• Progression (P):
  • Reassess functional status every 2–4 weeks. Increase intensity, complexity, or repetitions as pain decreases and strength increases.
  • Should pain or fatigue worsen, reduce load and consult a professional rehabilitation therapist.
• Special Precautions:
  • If severe pain intensifies, numbness spreads, or dorsiflexion strength fails to improve or worsens, seek a prompt medical review.
  • During soft tissue or nerve recovery periods, exercise intensity must be carefully monitored, particularly for the ankle and foot.

Disclaimer:
This report is based solely on existing data for reference and does not substitute for in-person consultation or professional medical advice. In the event of any uncertainties or worsening symptoms, please seek timely medical attention and follow the guidance of a specialist.