History: A 25-year-old woman with swelling and pain after bumping her right forearm.
病史：25岁女性，右前臂碰撞后肿胀、疼痛。
Radiographs are shown below.
平片如下所示。
Additional history and MR images
Additional clinical history: Patient states that she bumped her distal right arm just above the wrist about three years ago and had swelling at the time. X-ray showed that there was an abnormality, and she had a bone biopsy, which showed only evidence of necrotic marrow. The area was clinically stable until two to three months ago when she said the area seemed to almost overnight develop into an area of swelling and pain that increased very rapidly.
补充病史：三年前碰撞了右臂远端腕部上方并开始肿胀，当时行X线检查有异常，骨穿刺活检提示骨髓坏死。之后病变较稳定，直到2-3个月前迅速肿胀并疼痛。
MR images are shown below.
MRI图像如下所示。
Findings
Radiographs: In the distal one-third of the radius, there is a mixed lytic and sclerotic destructive lesion with soft-tissue component.
MRI: There is a solid enhancing mass arising from the distal radial diaphysis and metadiaphysis with extension into the interosseous membrane between the radius and ulna. There is enhancement and edema along the radial diaphysis and interosseous membrane and within the radius.
影像表现
平片：桡骨远段1/3可见一骨质溶解及硬化混合的破坏性病变，合并软组织肿块。
MRI：桡骨远段1/3骨干及干骺端实性肿物，病变膨胀至尺桡骨之间的骨间膜，相应区域有强化及水肿。
Differential diagnosis
The differential diagnosis for an aggressive diaphyseal lesion in a long bone of an adult would include the following:
- Metastasis
- Osteomyelitis
- Plasmocytoma
- Lymphoma
- Ewing\’s sarcoma
- Osteosarcoma
- Chondrosarcoma
- Langerhans cell histiocytosis
Diagnosis:
Ewing\’s sarcoma of the forearm
鉴别诊断
成人、长骨、骨干、侵袭性病变：
- 转移瘤
- 骨髓炎
- 浆细胞瘤
- 淋巴瘤
- 尤文肉瘤
- 骨肉瘤
- 软骨肉瘤
- 朗格汉斯细胞组织细胞增生症
诊断：（前臂）尤文肉瘤。
Key points
Ewing\’s sarcoma
- Ewing\’s sarcoma comprises about 5% of biopsied tumors.
- Peak incidence is between ages 10 and 25.
- There is a predilection for Caucasians (95%) and males (1.5:1).
- Most cases (90%) are solitary and 10% are multiple.
- They are usually located in the major long bones: femur (25%) and humerus (8%); also located in flat bones: pelvis (20%) and ribs (11%).
- Distribution: Found in diaphysis in 35% of cases, metadiaphysis in 59%, and epiphysis 5%.
- There is a periosteal reaction in 85% of cases, “onion skin” in 55%, and cortical thickening in 20%.
- Pathologic fracture seen in 10% to 15% of cases, and soft-tissue calcifications in 10% of cases.
- Soft-tissue mass is present in 90% of cases.
知识点
尤文肉瘤
- 在被活检肿瘤中约占5%；
- 发病高峰年龄在10-25岁之间；
- 多见于白种人（95%），男性多见；
- 90%为单发，10%为多发；
- 通常位于粗大长骨：股骨（25%）、肱骨（8%），也可见于扁骨：骨盆（20%）、肋骨（11%）；
- 部位：骨干（35%）、干骺端（59%）、骨骺（5%）；
- 85%可见骨膜反应，55%呈“葱皮样”表现，20%表现为骨皮质肥厚；
- 10%-15%可见病理性骨折，10%可见软组织钙化；
- 90%可见软组织肿块。