Medical Analysis Report

I. Radiological Findings

Based on the provided X-ray, CT, and MRI images, symmetrical increases in bone density can be observed in both lower limbs (especially involving the knee joints and tibia-fibula regions). These changes primarily affect the metaphyseal and diaphyseal areas. The specific features are as follows:

• On the X-ray films: distinct bilateral sclerotic lesions are seen at the distal femur and proximal tibia, with relatively clear boundaries. The cortical bone appears thickened, and the medullary cavity is involved.
• On the CT cross-sectional images: multiple patchy or irregular sclerotic areas are noted within the medullary cavity, with potentially indistinct boundaries between the lesions and the surrounding normal bone, suggesting possible infiltration by mononuclear or multinuclear histiocyte-like cells.
• On MRI: low signal intensity (hypointensity) on T1WI and high signal intensity on T2WI in the medullary cavity are observed, with a smooth interface between the cortical bone and adjacent soft tissues, indicative of a gradually infiltrative process predominantly presenting with bone sclerosis.
• Pulmonary imaging shows a few interstitial changes or hazy opacities, suggestive of possible lung involvement or fibrosis.

Overall, the radiological findings demonstrate symmetrical sclerosis, particularly at the metaphyses of long bones, with minimal soft tissue infiltration, raising the possibility of a rare histiocytic infiltrative disorder.

II. Potential Diagnoses

1. Erdheim-Chester Disease (ECD)
   This disease is a rare form of non-Langerhans cell histiocytosis and can present with the characteristic bilateral, symmetrical sclerotic lesions at the metaphyses of long bones. It often involves the bones, cardiovascular system, central nervous system, and other systems. Radiologically, it is marked by bone sclerosis and medullary infiltration, consistent with the findings in this case.
2. Langerhans Cell Histiocytosis (LCH)
   Although it is more common among children and adolescents, LCH can also appear in adults with bone destruction or sclerosis. Differentiating LCH from ECD requires additional immunohistochemical markers (e.g., CD1a, S100, CD68) and pathological examination.
3. Other Sclerotic Bone Lesions
   Such as metastatic bone lesions (e.g., from prostate cancer or sclerotic metastases due to mithramycin therapy) or myelofibrosis. However, these conditions typically lack the distinct bilateral symmetrical infiltrative pattern seen in this case and would require correlation with clinical history and laboratory tests.

III. Final Diagnosis

Considering the patient’s chronic progressive bone pain, the characteristic symmetrical sclerotic infiltration of the lower extremities (particularly the distal femur and tibia), the low-T1 and high-T2 signal changes on imaging, and the resemblance to findings described in the literature, the most likely diagnosis is Erdheim-Chester Disease (ECD). Further confirmation with immunohistochemistry (CD68 positive but CD1a negative) and pathological examination is recommended.

IV. Treatment Plan and Rehabilitation Program

1. Overview of Treatment Strategies

• Pharmacological Therapy: Glucocorticoids are often the first choice to alleviate symptoms and reduce histiocyte infiltration. In some cases, interferon alpha, chemotherapy (such as cladribine), targeted therapy (related to BRAF V600E mutations), or immunotherapy may be used to address systemic disease.
• Radiotherapy: Low-dose radiotherapy may be considered for severe local symptoms or cases involving critical organs (e.g., the central nervous system) to relieve local symptoms.
• Surgical Intervention: Primarily reserved for lesions threatening functional status or necessitating biopsy. Surgical decompression or repair may be considered when lesions compress vital structures (such as the optic nerve or hypothalamus) or cause fractures.

2. Rehabilitation and Exercise Prescription Recommendations

• Initial Stage:
  • Focus on low-intensity joint range-of-motion exercises, such as gentle joint mobility drills, stretching, and walking, avoiding heavy loads, intense or high-impact movements.
  • Frequency may start at 3-4 sessions per week, lasting 20-30 minutes each time. Adjust based on bone pain and patient tolerance.
  • Pay attention to bone stability and take fall prevention measures to avoid pathological fractures.
• Intermediate Stage:
  • Depending on disease control, gradually introduce strength exercises under the guidance of a physician or rehabilitation therapist, such as resistance band training or light dumbbell workouts, while avoiding excessive loading.
  • Frequency may be increased to 4-5 sessions per week; intensity can be gradually stepped up based on individual tolerance.
  • Combine endurance training (e.g., moderate cycling or swimming), monitoring respiratory and heart rate changes, especially in patients with possible lung or cardiac involvement.
• Later Stage:
  • Progress to maintenance and enhancement phases, focusing on functional training while continuing to monitor bone health and overall status.
  • Frequency may be maintained at around 5 sessions per week, with session duration increasing to 40-60 minutes.
  • If disease progression is effectively controlled, introduce light aerobic exercises or flexibility training according to individual capacity.
• Safety and Individualization:
  • Closely monitor bone pain, cardiopulmonary function, and overall fatigue levels, avoiding high-impact exercises.
  • Regularly recheck bone density, imaging findings, and relevant blood tests as needed, and adjust the rehabilitation plan accordingly.

This rehabilitation approach follows the FITT-VP principle (Frequency, Intensity, Time, Type, Progression, and Individual differences), emphasizing a gradual and individualized process. All exercises should be carried out under the guidance and supervision of specialized physicians or rehabilitation therapists.

V. Disclaimer

This report is a reference analysis based on the existing medical history and radiological findings and does not substitute for an in-person consultation or professional medical opinion. Please consult relevant specialists for any modifications to the diagnostic or treatment plans to ensure personalized and safe medical care.