History: A 45-year-old woman presents with mild chest pain and neck soreness after being in a motor vehicle collision in which the airbags deployed. The patient had no other significant medical history.

病史：45歲女性在機動車碰撞安全氣囊打開后出現輕度胸痛和頸部酸痛?；颊邲]有其他重要的病史。

Frontal and lateral radiographs of the chest were obtained. 

胸部正側位片

Chest CT images

a noncontrast-enhanced CT scan of the chest was performed. 

行胸部CT平掃

MRI/PET images

For further workup, a contrast-enhanced MRI scan of the chest and a PET scan were performed. 進一步行胸部MRI增強掃描及PET掃描

Findings

• Radiographs: There is an opacity along the right mediastinum, which on the lateral view appears to be located within the anterior mediastinum.

• Chest CT: A lobulated homogeneous soft-tissue density nodule is present in the anterior mediastinum. No enlarged lymph nodes are present.

• Chest MRI: A right anterior mediastinal nodule abutting the superior vena cava and ascending aorta demonstrates multiple internal cystic areas and heterogeneous enhancement.

• PET: There is an FDG-avid right anterior mediastinal nodule. No findings of metastatic disease.

影像表現：

• 平片：沿縱隔右緣見一陰影，側位片示病灶位于前縱隔；

• 胸部CT：前縱隔一分葉狀均勻軟組織密度結節(jié)灶，未見增大淋巴結；

• 胸部MRI：右前縱隔結節(jié)，鄰近上腔靜脈及升主動脈，瘤內見多發(fā)囊變區(qū)，不均質強化；

• PET：病灶FDG代謝增高，未見轉移灶。

Differential diagnosis

• Thymoma/thymic carcinoma

• Thymic hyperplasia/rebound

• Lymphoma

• Teratoma and other germ cell tumors

鑒別診斷：

• 胸腺瘤/胸腺癌

• 胸腺增生

• 淋巴瘤

• 畸胎瘤及其他生殖細胞瘤

Diagnosis: Thymoma (stage IIA with capsular invasion at surgery)

最后診斷：胸腺瘤（IIA期 侵犯包膜）

Key points

Thymoma

Pathophysiology and epidemiology

Thymomas are rare tumors originating from epithelial cells of the thymus that develop in the anterior mediastinum.

Most patients with thymic epithelial tumors present between ages 40 and 60.

病理生理學及流行病學

• 胸腺瘤是起源于胸腺上皮細胞的少見腫瘤（在我國并不少見），位于前縱隔。

• 大部分胸腺上皮源性腫瘤患者的年齡在40-60歲之間。

Clinical presentation

• Many patients are asymptomatic at the time of diagnosis, with the tumor discovered incidentally during workup for other medical issues.

• Symptoms are generally due to mass effect in the anterior mediastinum and include cough, chest pain, and shortness of breath/wheezing.

• Approximately 50% of patients with a thymoma are diagnosed with myasthenia gravis. Other associations include hypogammaglobulinemia and autoimmune red cell aplasia.

臨床表現：

• 許多患者在診斷時尚無癥狀，為查體時偶然發(fā)現；

• 大部分癥狀由于病變在前縱隔的占位效應導致，如咳嗽、胸痛、氣短、喘息；

• 約50%的胸腺瘤患者患有重癥肌無力，其他相關表現有低丙種球蛋白血癥和自身免疫性紅細胞再生障礙。

Imaging findings

• Radiographs: Thymomas appear as lobulated soft-tissue masses in the anterior mediastinum.

• CT:

• On CT, they appear as soft-tissue attenuation masses located in the anterior mediastinum.

• Variable calcifications may be present.

• MRI:

• Thymomas are generally isointense to muscle on T1-weighted imaging.

• They have heterogeneous signal on T2-weighted imaging, with possible cystic areas.

• Variable enhancement is seen. May see linear enhancing septa.

• PET:

• Most thymic epithelial neoplasms are mildly FDG-avid.

• Dedifferentiated tumors such as thymic carcinoma having increased FDG uptake.

影像表現：

• 平片：胸腺瘤表現為前縱隔分葉狀軟組織腫物；

• CT：表現為前縱隔軟組織密度腫物，可見不同程度的鈣化；

• MRI：胸腺瘤在T1WI上主要呈等信號（與肌肉相同），T2WI上呈不均質高信號，可見囊變區(qū)；強化程度不同，可見線樣強化的分隔影；

• PET：大部分胸腺上皮源性腫瘤為輕度FDG代謝增高，去分化腫瘤例如胸腺癌為FDG明顯攝取。

臨床分期：