Medical Imaging Analysis Report

1. Imaging Findings

Based on the provided X-ray, CT, and MRI images, a large area of abnormality in the right proximal ulna (near the elbow joint) is observed, specifically characterized by:

• On the X-ray images, the lesion margin is relatively well-defined, the cortical bone is largely intact, and the lesion area shows a “ground-glass” appearance or a mild mixture of sclerotic and radiolucent zones.
• CT reveals a mix of fibrous and osseous densities within the medullary cavity, with certain regions appearing relatively low in density. In some areas, there is noticeable osteopenia or lucent areas, and a certain degree of erosion or “concavity” at the subchondral margin, although no apparent joint space narrowing is identified.
• MRI shows predominantly mixed signals in the medullary cavity. T1WI mostly appears as intermediate to low signal intensity, while T2WI reveals various degrees of high signal areas and a few low-signal foci, suggesting the presence of varying degrees of fibrous tissue and bony changes. The lesion extends to the proximal ulnar physis and is close to the articular surface, resulting in localized cartilage bulge or compression.
• No obvious periosteal reaction or significant soft tissue swelling was observed.

The overall imaging characteristics indicate that the lesion is primarily related to a fibrous-osseous proliferative process within the bone, with a wide extent. Involvement of the physis and its proximity to the articular surface is relatively rare.

2. Potential Diagnoses

Combining the patient’s age of 16, clinical presentation (right elbow pain for 5 weeks without a clear history of trauma), and the imaging findings, the main differential diagnoses are as follows:

1. Fibrous Dysplasia
   Cause: A developmental anomaly typically occurring in adolescents and young adults, where fibrous-osteoblast-like tissue replaces the bone marrow.
   Characteristics: Lesions often show a “ground-glass” or mixed-density appearance with relatively well-defined borders and usually no significant periosteal reaction. They can involve the metaphysis-epiphysis of long bones and can appear in different segments.
2. Giant Cell Tumor
   Cause: Commonly occurs around the epiphysis-metaphysis of long bones, most frequently seen in young adults after closure of the growth plates until about 30 years old.
   Characteristics: Typically shows expansile lytic destruction with well-defined margins, often extending to the articular surface. However, giant cell tumors more commonly present with a prominent expansile “soap bubble” appearance, cortical thinning, and clinically significant pain.
3. Chondroblastoma
   Cause: Usually arises in the epiphysis near a joint, frequently in adolescents.
   Characteristics: The lesion commonly appears radiolucent or of intermediate density, and may present with a sclerotic rim. Imaging often shows chondroid calcifications or a lobulated contour.

3. Final Diagnosis

Considering the patient’s age, symptoms, and imaging features, “Fibrous Dysplasia (Fibro-Osseous Dysplasia)” best matches the overall presentation. The ground-glass appearance, relatively distinct borders, lack of significant periosteal reaction, and the wide lesion extent approaching the articular surface are all consistent with monostotic fibrous dysplasia. Although involvement of the epiphysis and close proximity to the joint surface is uncommon, the lesion’s density characteristics and clinical course support this diagnosis. A biopsy could be performed for further confirmation if needed.

4. Treatment and Rehabilitation Plan

For monostotic fibrous dysplasia, clinical management typically depends on symptom severity and the stability of the bony structure:

• Conservative Management: If the lesion is contained, elbow function remains intact, and pain is tolerable, observation and symptomatic treatment may be considered initially. Use of analgesics or NSAIDs can help alleviate pain, if necessary.
• Surgical Intervention: If the lesion is large, causes significant joint dysfunction, or poses a risk of pathological fracture, curettage with bone grafting or internal fixation may be considered. When necessary, resection and reconstruction or corrective surgery can be performed. If the articular surface is substantially compromised, reconstruction of the elbow joint surface or grafting might be required to maintain joint stability.

Rehabilitation/Exercise Prescription (FITT-VP Principles):

1. Type: Emphasize moderate or low-intensity upper extremity functional exercises, such as range-of-motion (ROM) exercises, light resistance exercises (using resistance bands or light dumbbells), swimming, and other low-impact activities.
2. Frequency: For acute pain, perform ROM exercises 1-2 times per day. After pain subsides, engage in low-intensity strength training 3-4 times per week.
3. Intensity: Start with a level that does not provoke or only mildly aggravates pain. Resistance can be around 30-40% of the maximal load. As pain improves and joint function recovers, adjust intensity accordingly.
4. Time: Each session should last about 20-30 minutes, modified according to joint response, with each movement done for 8-12 repetitions per set, for 2-3 sets. If any significant increase in pain or swelling occurs, reduce intensity or stop immediately.
5. Progression: Gradually increase resistance or activity duration as pain decreases and bone healing progresses, eventually returning to normal daily activities. If no complications or functional impairments occur, maintain moderate exercise intensity to strengthen muscles and stabilize the joint.

During rehabilitation, pay close attention to pain, swelling, and the structural integrity of the bone. In cases of fragile bone or a high risk of pathological fracture, carefully regulate exercise intensity and joint loading.

5. Disclaimer

This report is based on the available imaging data and clinical information for reference only, and should not be considered a substitute for an in-person consultation or professional medical advice. If any questions or changes in condition arise, please seek further evaluation and treatment at a qualified medical institution.