MedPix® Patient Chart - Case No: 2467 :: - Review Images

9 y.o. girl with several month history of dull, intermittent, substernal chest pain - relieved by sitting up and treated with NSAIDs.

Physical examination unrevealing. EKG normal.

- Review Images for PT: 2467

• PA and lateral chest radiographs: Large, circumscribed anterior mediastinal mass abutting the ascending aorta, pulmonary artery, and left heart border. No evident adenopathy or pleural effusion.

• Contrast-enhanced chest CT: Circumscribed, heterogeneous anterior mediastinal mass containing components with fluid and fat attenuation but no calcifications. The mass abuts and displaces the thymus. No adenopathy or evidence of local invasion.

- Review Images for PT: 2467

» The differential diagnosis for a child with a mediastinal mass on CXR includes:

• thymoma
• thymic carcinoid
• thymic carcinoma
• thymic cyst
• thymolipoma
• lymphoma
• germ cell tumors
• parathyroid adenoma
• lymphangioma
• intrathoracic goiter

» The most common of these are thymoma, germ cell tumor, substernal goiter, and lymphoma. All the other conditions are rare.

» In this patient the CT appearance, especially the presence of fat, is highly specific for a teratoma.

» Additionally, the lack of contiguity of the mass with the thyroid makes goiter very unlikely, the patient's sex makes a malignant germ cell tumor unlikely, the absence of adenopathy elsewhere argues against lymphoma, and her age makes thymoma unlikely.

- Review Images for PT: 2467

Dx: Mediastinal Teratoma

Dx Confirmed by: Imaging, surgery, pathology

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In addition to imaging, evaluation of an anterior mediastinal mass includes measurement of serum anti-acetylcholine receptor antibodies, seen with thymoma, and AFP and beta-HCG seen with some malignant germ cell tumors. Patients with primary masses will usually undergo surgical resection. The presence of lymphadenopathy (implying lymphoma or metastatic disease) or elevated serum AFP or beta-HCG should prompt limited biopsy followed by oncologic consulation and chemotherapy or radiotherapy when appropriate. Resection of residual tumor will follow in some cases.

In this case the mature teratoma was resected succesfully.

Submitted by Chris Lebrun and Joon Yun, medical students.

Mediastinal teratomas are germ cell tumors composed of tissue arising from more than one of the three primitive germ cell layers. Teratomas can contain teeth, skin, hair, bone, cartilage, or bronchial, intestinal, or pancreatic tissue. Rarely, a mediastinal teratoma contains fetal tissue and is therefore termed "immature." Immature teratomas are considered malignant because of their tendency to metastasize or invade local tissues. Teratomas account for 60-70% of mediastinal germ cell tumors. They are tumors of children or young adults. Unlike the other mediastinal germ cell neoplasms, which are universally malignant and occur almost exclusively in males, teratomas occur with equal frequency in both sexes.

Plain films may demonstrate calcifications in up to 26%, sometimes recognizable as teeth or bones. Teratomas typically manifest on CT as heterogeneous anterior mediastinal masses containing soft tissue, fluid collections, fat, calcification, or any combination of the four. Fat and calcification occur frequently, but lesions without fat or calcium are not uncommon. Fat-fluid levels, considered highly specific for the diagnosis of benign ("mature") teratoma, are uncommon. Surgical excision is curative.

Submitted by Chris Lebrun and Joon Yun, medical students.