Mature Teratoma

Answer

Diagnosis: Mature Teratoma

Discussion: The most common tumors of the anterior mediastinum include thymic neoplasm and lymphoma, but the prevalence of the different abnormalities varies markedly according to both age and gender. Thymoma is the most common anterior mediastinal mass and most commonly occurs in middle aged people. Benign teratomas are typically seen in younger patients and account for ~ 25% of anterior mediastinal masses in ages 10-19, 10-15% in ages 20-49, and <5% over age 50 in both men and women. Mediastinal germ cell tumors have also been associated with Klinefelter’s syndrome

Patients are usually asymptomatic from a mediastinal mass but may report symptoms due to compression of mediastinal structures (chest pain, dyspnea, cough, pulmonary infection). Rarely the patient may have expectoration of hair (trichoptysis) and is pathognomonic symptom.³ Beta HCG is elevated with yolk sac tumor. Alpha-fetoprotein is elevated with choriocarcinoma.

Anterior mediastinal masses often share common hallmarks on chest radiography. They usually silhouette the heart and create an obtuse angle to the mediastinum and lungs. The anterior junction line is often disrupted or thickened with anterior mediastinal masses and, as in our case, there may also be a “Hilum overlay sign” – the ability to see hilar vessels through the mass means it is either anterior or posterior to it. Lateral radiographs typically can definitively compartmentalize into anterior, middle, or posterior mediastinum.

CT

·          Fluid attenuation cysts (90%)

·          Fat fluid level is highly specific for teratoma, but only seen in ~ 10% of cases

·          Fat attenuation cyst content (75%)

·          Calcification best detected on CT (50%)

MRI

·          Generalized anterior mediastinal masses:

o    Superior to CT in:

§   Differentiating cystic from solid masses (eg. thymic cysts from thymic neoplasms)

§   Discerning cystic/necrotic components within solid masses

§   Discerning thymic hyperplasia from thymic tumors

·          Teratoma

o    Fat components are T1 hyperintense

o    Proteinaceous fluid, hemorrhage may be T1 hyperintense

o    Confirm fat content with fat suppression

o    Cystic components exhibit low signal on T1 and high signal on T2

Staging/Grading/Classification

Teratomas are commonly classified by using the Gonzalez-Crussi grading system: 0, mature; 1, immature/probably benign; 2, immature/possibly malignant; and 3, frankly malignant.

·          Mature teratoma is most common (70%)

o    Comprised of well differentiated elements

o    Generally benign although have malignant potential

§   Benign teratomas are seen equally in men and women

§   Malignant teratoma is more common in men

o    Usually slow growing

·          Immature teratoma

o    contains immature elements (neuroectoderm)

o    more benign in kids, aggressive in adults

Treatment

Surgical excision is the treatment of choice because teratomas have a tendency to be well encapsulated and rarely invade adjacent structures. Complete surgical resection is usually curative, but chemotherapy or radiation therapy may be indicated depending on malignant potential and clinical circumstances. Follow-up imaging should be performed to evaluate for residual or recurrent disease and any postoperative complications. Malignant teratoma carries very poor prognosis. Mature teratoma carries great prognosis.

References:

1.        Carter BW, Okumura M, Detterbeck FC, Marom EM. Approaching the patient with an anterior mediastinal mass: a guide for radiologists. J Thorac Oncol. 2014;9(9 Suppl 2):S110-8.

2.        No TH, Seol SH, Seo GW, et al. Benign Mature Teratoma in Anterior Mediastinum. J Clin Med Res. 2015;7(9):726-8.

3. Yalagachin GH. Anterior mediastinal teratoma- a case report with review of literature. Indian J Surg. 2013;75(Suppl 1):182-4.