Radiological Findings

Based on the provided anteroposterior pelvic X-ray, MRI, and CT images, localized lesion characteristics are observed in the left iliac bone and the proximal femoral region, specifically manifested as follows:

• On the plain radiograph: mild cortical thickening and sclerosis can be seen in the region of the left femoral neck, with reactive bone proliferation in the surrounding area. The lesion area shows a focal radiolucent lesion (radiolucent or low-density zone), suspected as the “nidus” (lesion core).
• On MRI: on T1-weighted images, the lesion core shows low to intermediate signal, with obvious edema or reactive changes in the surrounding bone marrow and soft tissue. On T2-weighted images, signal characteristics may vary depending on calcification or ossification components, but often indicate surrounding edema.
• On CT: the lesion appears as a round or oval low-density focus (potentially with calcification or ossification in the core), with significant cortical thickening and sclerosis around it. This is very helpful in confirming a focal “nidus” in the bone cortex.

Overall, the imaging presents the typical feature of a “small radiolucent focus + reactive sclerosis,” with the lesion confined to the cortical bone. This finding is consistent with the clinical presentation of nocturnal pain relieved by non-steroidal anti-inflammatory drugs (NSAIDs).

Potential Diagnoses

Based on the patient’s age, symptoms, and imaging findings, the following potential diagnoses and brief rationale are considered:

1. Osteoid Osteoma: Common in children and adolescents, chiefly characterized by nocturnal pain, often relieved by aspirin or NSAIDs. Imaging typically reveals a small, focal radiolucent area (nidus) in the cortex with surrounding sclerosis.
2. Brodie’s Abscess: A localized form of chronic osteomyelitis, which can sometimes present with a focal radiolucent lesion. However, it often correlates with infection-related symptoms or elevated inflammatory markers, and its lesion borders may be less regular than those of osteoid osteoma.
3. Stress Fracture: Commonly found in weight-bearing bones or in individuals with high levels of physical activity, typically presenting as linear low-density cracks or periosteal reactions on imaging. Clinical symptoms are usually related to activity.
4. Eosinophilic Granuloma: Often seen in children, can present with lytic bone destruction, but usually exhibits a clear destructive margin, periosteal reaction, and soft tissue involvement.
5. Other Uncommon Cortical Bone Tumors or Tumor-Like Lesions: For instance, osteoma or osteochondroma, etc. However, their morphological characteristics and clinical presentation are not fully consistent with this case.

Final Diagnosis

Combining the imaging findings, the typical nocturnal pain that responds to analgesics, as well as the patient’s age and sex characteristics, the most likely diagnosis is: Osteoid Osteoma.

If there is still uncertainty in imaging or clinical aspects, further CT perfusion imaging (Perfusion CT) or, if necessary, a pathological biopsy may be performed to confirm the diagnosis.

Treatment Plan and Rehabilitation Program

Based on the benign nature of osteoid osteoma and the patient’s current symptoms, the main treatment strategies include:

• Conservative Treatment: Oral NSAIDs to relieve pain, or short-term analgesic medications for symptom management.
• Minimally Invasive Interventional Treatment: CT-guided radiofrequency ablation (RFA) is the first choice, being simple, offering a high success rate, and involving low complication risks.
• Surgical Treatment: If the lesion location is special or minimally invasive treatment is not feasible, surgical excision of the lesion may be considered, although it is usually only performed under special circumstances.

Rehabilitation/Exercise Prescription Recommendations (following the FITT-VP principle: Frequency, Intensity, Time, Type, Progression, Volume):

1. Early Stage (1-2 weeks after RFA or other treatments):
   • Primarily focus on range-of-motion exercises and mild muscle-strengthening exercises.
   • Frequency: 3-4 times per week, avoiding excessive load.
   • Intensity: perform gentle joint mobilization and low-intensity functional training without notable pain.
2. Intermediate Stage (3-6 weeks post-surgery or treatment):
   • Maintain joint flexibility training and begin increasing lower limb strength training (e.g., transitioning from non-weight-bearing to partially weight-bearing closed-chain exercises).
   • Frequency: 3-4 times per week, with intensity gradually increased to a moderate level.
   • Time: 20-30 minutes each session; combine with basic functional exercises and monitor for pain responses.
3. Late Stage (6 weeks or more post-surgery or treatment):
   • Increase core strength, lower limb strength, and endurance training. As appropriate, gradually transition to jogging, swimming, cycling, or other aerobic activities.
   • Frequency: 3-5 times per week, with intensity increased based on pain tolerance and functional recovery.
   • Time: gradually extend to 30-45 minutes per session, adjusting according to individual tolerance.
   • During this period, regular follow-up is recommended to evaluate bone maturity and lesion stability.

Throughout the rehabilitation process, exercise volume and intensity should be adjusted in a timely manner based on the patient’s recovery status, and pain or other discomfort should be monitored. If significant pain, joint swelling, or other symptoms appear, exercise should be suspended or reduced, and professional guidance from a physician or rehabilitation therapist should be sought.

Disclaimer:

This report is a reference analysis based on currently provided medical history and imaging data, and cannot replace an in-person consultation or professional medical advice. The specific treatment plan should be determined through comprehensive evaluation by specialized physicians in conjunction with the actual clinical situation.