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Clinical History

1 year complained of pain over the elbow not relieved by fans. It wasn’t associated with a traumatic event and there wasn’t night exacerbation.

Imaging Findings

1 year complained of pain over the elbow not relieved by fans. It wasn’t associated with a traumatic event and there wasn’t night exacerbation. His general practitioner suggested non steroidal anti-inflammatory medication along with physiotherapy, but there was no improvement.. The plain radiograph (fig 1) showed small rounded lucency within the cortex of ulna (the nidus) with limited surrounding sclerosis and dense periosteal reaction. MR imaging confirmed RX imaging (fig 2): synovial thickening, joint effusion and olecran oedema. There wasn’t soft tissue edema adjacent to the tumor. The 2 mm thick AXIAL CT scans (fig 3) showed a lytic lesion (small rounded nidus) and a thick periosteal reaction of the ulna. The patient underwent surgical excision and the excised lesions‘ histology showed osteoid osteoma. He is now asymptomatic.

Discussion

Osteoid osteoma is a benign skeletal neoplasm of unknown etiology.The tumor is usually smaller than 1.5 cm in diameter. Osteoid osteoma can occur in any bone, but in approximately two thirds of patients, the appendicular skeleton is exceptionally involved; the skull and facial bones are involved exceptionally. Most patients with osteoid osteoma are young (10-30). An ossification center is rarely affected. The lesion initially appears as a small sclerotic bone island within a circular lucent defect. The tumors may regress spontaneously. The tumor consists of an ovoid or spherical nidus of osteoid-rich tissue and interconnected bone trabeculae superimposed on a background of highly vascularized connective tissue containing large dilated vascular channels. Osseous and osteoid tissue ‘s amount varies within the nidus and is reflected in its radiologic opacity. Osteoid osteoma is classified as cortical (more common), cancellous or subperiosteal. The classic presentation is the one of focal bone pain at the site of the tumor. The condition worsens at night and increases with activity, and it is dramatically relieved with small doses of aspirin. An intracapsular lesion often provokes a considerable intra-articular inflammatory response, mimicking erosive arthropathy, crystal arthropathy, or infective arthritis. Approximately one half of patients with intra-articular lesions may have complications of osteoarthrosis 1.5-22 years after the onset of symptoms. Marked weakness associated with muscular atrophy may rarely affect the involved limb, particularly when the tumor is long-standing. Intra-articular lesions cause synovial thickening or inflammation and joint effusion, which may be read The diagnosis of intra-articular osteoid osteoma is often delayed because it may be confused with other forms of inflammatory or infective arthritis, non specific synovitis or Legg-Calvè-Perthes disease. Radiography is the initial examination of choice; radiographic features depend on the site of involvement and the patient’s age. A circular or ovoid lucent defect is seen in 75% of patients. The site of the tumor determines the degree of bone sclerosis. In medullary tumors, sclerosis is minimal or absent. Cortical and subperiosteal tumors provoke considerable sclerosis. Long-standing tumors demonstrate more sclerosis. Children also mount more of a sclerotic response than do adults. In subarticular and intracapsular tumors, reactive sclerosis may occur relatively distant to the lesion. Intra-articular tumors may show joint effusion associated with the premature loss of cartilage. Osteoarthrosis affects approximately one half of patients with intra-articular tumors. Regional osteoporosis rarely affects patients, presumably as a result of disuse. This may be depicted as an area of osteopenia around a joint. The MR imaging protocol included T2 weighted FSE, T2 weighted Gradient and STIR in sagittal and coronal plane. Bone marrow edema is depicted around the nidus in approximately 60% of patients. Perinidal edema is more pronounced in young patients. CT is a accurate diagnostic tool for the precise localization of the nidus,

Differential Diagnosis List

Intraarticular osteoid osteoma

Final Diagnosis

Intraarticular osteoid osteoma

Liscense

Figures

Fig 1 RX Typical nidus of osteoid osteoma, with periosteal bone sclerosis.

Fig 2 Nonenhanced SPIN ECHO T2 weighted demonstrates the nidus, with a central low-signal-intensity corresponding to the sclerotic area in the CT scan in fig 3.

Fig 3 The 2 mm thick AXIAL CT scan shows a lytic lesion and a thick periosteal reaction of the ulna.

Fig 4 STIR: Synovial thickening, joint effusion and olecran oedema. Oedema adjacent to the tumour.

Medical Imaging Analysis Report

I. Imaging Findings

Based on the provided elbow X-ray, MRI, and CT images, the following main features can be observed:

X-ray: Near the elbow joint (often in the distal humerus or proximal ulna/radius), a localized small area of radiolucency (“lytic” lesion) is visible, surrounded by a sclerotic margin or local bony overgrowth and increased density. This is consistent with a typical nidus and surrounding reactive sclerosis.
MRI (T2/STIR sequences): A round or oval high signal area can be seen at the suspected lesion site, with significant local bone marrow edema signal around it, indicating inflammatory or reactive edema around the lesion.
CT: Demonstrates the morphology of the nidus more clearly, appearing as a small, round or ovoid low-density radiolucent area, surrounded by thickened and sclerotic cortical bone. The lesion is small in diameter (usually less than 1.5 cm).

The above imaging changes suggest a “small pit-like” lesion in the cortical bone or near the joint, with a distinct sclerotic margin and some degree of reactive bone changes (sclerosis, hypertrophy, and edema).

II. Differential Diagnosis

Based on the patient’s young age (18 years old), the size and morphological characteristics of the elbow lesion, and the imaging findings, possible diagnoses include:

Osteoid Osteoma:
- Commonly occurs in adolescents and young adults, often found in the cortical bone of the long bones or near joints.
- Typical imaging features are the central nidus and surrounding bony sclerosis.
- Clinically, it may present with localized pain, often worse at night, but not all patients experience nocturnal aggravation or marked relief by aspirin.
Osteoblastoma:
- Pathologically similar to osteoid osteoma, but usually larger than 1.5–2 cm.
- May show similar lytic changes, but with a greater extent, often accompanied by bone destruction or compression of surrounding structures.
Chronic Inflammatory Lesion or Infection (e.g., Chronic Osteomyelitis):
- Shows local bone destruction with a sclerotic margin, but often with systemic or local inflammatory manifestations. Imaging may reveal an irregular radiolucent area, sequestrum, or involucrum formation.
Other Periarticular Lesions (e.g., Enchondroma, Synovial-related lesions, etc.):
- Rare in this location, and imaging usually differs significantly from that of osteoid osteoma.

III. Final Diagnosis

Considering the patient’s age (18 years old), chronic elbow pain, and the characteristic nidus with surrounding sclerotic reaction on imaging, the most likely diagnosis is:

Osteoid Osteoma.

If further confirmation is required, a CT-guided biopsy can be considered, or a typical clinical response (such as marked pain relief with NSAIDs) can be used as supporting evidence.

IV. Treatment Plan and Rehabilitation Program

1. Treatment Strategies

Conservative Treatment: For patients with mild symptoms or tolerable pain, NSAIDs can be used to relieve pain, along with regular imaging follow-up.
Minimally Invasive Ablation: Techniques such as radiofrequency ablation (RFA) or microwave ablation are effective for small lesions (<1.5 cm), with minimal trauma and quick recovery.
Surgical Resection: For cases not responding to conservative treatment, or for lesions in special locations causing joint or nerve compression, surgical removal can be performed with generally good prognosis.

2. Rehabilitation and Exercise Prescription

During symptom relief or postoperative rehabilitation, individualized rehabilitation training should be carried out according to the following principles (FITT-VP principle) to prevent joint stiffness and muscle atrophy:

Frequency: 2–3 rehabilitation sessions per week initially, potentially increasing to 3–4 times per week depending on pain and recovery.
Intensity: Start with low intensity to avoid significant pain or swelling. If surgery has been done, gradually progress under the guidance of a professional rehabilitation therapist or physician.
Time: Begin with 15–30 minutes per session, including exercises for joint range of motion and light resistance (e.g., resistance bands). Gradually extend the duration based on tolerance.
Type: When pain is minimal, begin with gentle joint mobilization and flexion/extension exercises, followed by progressive muscle-strengthening exercises (e.g., isometric or low-resistance). After pain subsides, incorporate combined upper limb exercises involving the shoulder and elbow.
Volume: Increase the number of sets or repetitions gradually as rehabilitation progresses.
Progression: Adapt the difficulty and intensity of exercises based on the patient’s tolerance and lesion healing, eventually incorporating stability training and functional resistance exercises.

Close observation of local pain, swelling, and joint range of motion is necessary throughout the rehabilitation process. If noticeable discomfort or worsening symptoms occur, revisit and adjust the rehabilitation plan promptly.

Disclaimer: This report is a reference analysis based on the currently available imaging and clinical data, and it should not replace in-person consultation or diagnosis and treatment by a professional physician. If you have any questions or changes in condition, please seek medical attention and discuss with a specialist.

Human Doctor Final Diagnosis

Intraarticular osteoid osteoma

AI Doctor