Imaging Findings

In the patient's right thigh region, ultrasound and MRI images show a well-defined multicystic lesion. Ultrasound reveals multiple cystic structures, with some compartments or membranous structures in certain cysts. MRI demonstrates a relatively large cystic lesion containing multiple cystic cavities or septa. On T2-weighted sequences, it appears hyperintense, while on T1-weighted sequences it appears relatively hypointense, with visible cyst walls or septa in some areas. The surrounding soft tissue maintains a generally regular shape, with no obvious signs of invasion into bone or major blood vessels.

Potential Diagnoses

1. Muscular Echinococcosis (Hydatid Disease): Considering the possibility that the patient comes from or resides in a hydatid-endemic region, combined with the clinical presentation (gradual, painless mass) and the imaging findings (multicystic lesion), echinococcosis is highly suggestive.
2. Intramuscular Hematoma or Cyst (e.g., Hematoma, Synovial Cyst): These can also appear as cystic structures on imaging but are usually associated with a history of trauma or joint pathology. Additionally, the ultrasound and MRI signal distribution may differ from the classic multi-compartmental or multiloculated features seen in hydatid disease.
3. Chronic Abscess (e.g., Tuberculous Cold Abscess): May present as a cystic lesion, but it is often accompanied by symptoms of infection or systemic indicators (fever, elevated white blood cell count, etc.). On imaging, peripheral enhancement or pronounced inflammatory reactions are often visible.
4. Other Rare Soft Tissue Tumors (e.g., Synovial Sarcoma or Myxoid Sarcoma): A small number of soft tissue tumors may exhibit cystic or cyst-like degeneration, but they are generally associated with local infiltration, and their signals and morphology often differ from a multiloculated cyst. Pathological examination is needed to make a clear distinction.

Final Diagnosis

Considering the patient's clinical presentation (painless, gradually enlarging right thigh mass), epidemiological background (especially if from a hydatid-endemic area), and imaging characteristics (multiple cystic vesicles, cystic walls, and septa), the most likely diagnosis is Muscular Echinococcosis (Hydatid Disease). If definitive confirmation is required, serological tests (anti-echinococcal antibodies) and/or intraoperative or postoperative pathological examinations can be conducted.

Treatment Plan and Rehabilitation Program

Treatment Strategy:

• Surgical Treatment: Primarily involves complete resection of the hydatid cyst or its contents, preventing cyst rupture and secondary infection. MRI with multiple-plane imaging can help in assessing the extent of the lesion and its relationships with nearby muscles, blood vessels, and neural structures for surgical planning.
• Pharmacotherapy: Anti-echinococcal medications (e.g., albendazole) may be used preoperatively or postoperatively to reduce the risk of recurrence.
• Observation and Follow-Up: For patients who are not candidates for surgery or face high surgical risk, periodic imaging follow-up is required to evaluate changes in the lesion, with subsequent treatment plans decided according to disease progression.

Rehabilitation and Exercise Prescription:

Following surgery, an individualized rehabilitation program should be developed to ensure safe and gradual recovery.

1. Early Recovery Phase (Weeks 1–2 Post-Surgery):
   • Focus primarily on maintaining basic function of the affected limb, performing gentle active or passive exercises under protective support (braces or bandages).
   • The range of motion should be limited to avoid pronounced pain or swelling, and excessive stretching or pressure on the surgical area should be avoided.
2. Intermediate Rehabilitation Phase (Weeks 3–6 Post-Surgery):
   • Under the guidance of a physician or rehabilitation therapist, gradually increase the intensity of muscle-strengthening exercises, such as low-resistance band training or light weight-bearing exercises.
   • Progressively expand the range of motion and increase the frequency of muscle conditioning sessions, aiming for three to four sessions per week, each lasting approximately 20–30 minutes.
3. Late Strengthening Phase (From Week 6 Post-Surgery onward):
   • In the absence of intense pain or swelling, higher-intensity muscle-strengthening and functional training can be undertaken (e.g., squatting, light jogging, or cycling).
   • Apply the FITT-VP principle (Frequency, Intensity, Time, Type, Volume, Progression), customizing the exercise intensity and duration based on the patient’s baseline fitness and cardiovascular status.

If the patient experiences obvious pain, local redness, swelling, or any other discomfort during training, exercise should be stopped immediately and medical or rehabilitation advice sought.

Disclaimer: This report serves only as a reference analysis based on current information and does not substitute for an in-person consultation or professional medical advice. If you have any questions or encounter any discomfort, please seek medical attention promptly.