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Teratomas: A Multimodality Review
Teratomas: A Multimodality Review Christine M. Peterson, MD,a Celine Buckley, MD,b Susan Holley, MD, PhD,c and Christine O. Menias, MDc
Germ cell tumors (GCTs) may occur in both children and adults and include a broad array of histologic subtypes, such as teratoma, seminoma (known as dysgerminoma in the ovary and germinoma in the pineal gland), choriocarcinoma, yolk sac tumor, embryonal cell carcinoma, and mixed GCT. In adults, GCTs occur most commonly in the gonads. In children, sacrococcygeal tumors predominate. Teratomas are a common form of GCT. They are defined histologically as containing tissues derived from all 3 germ cell layers: ectoderm, mesoderm (most teratomas contain fat, an imaging hallmark, which is a mesodermal derivative), and endoderm. Teratomas are also classified as mature or immature, depending on the degree of differentiation of its components, and in adults, immature tumors are more likely to exhibit malignant behavior.
Germ cell tumors (GCTs) may occur in both children and adults and include a broad array of histologic subtypes, such as teratoma, seminoma (known as dysgerminoma in the ovary and germinoma in the pineal gland), choriocarcinoma, yolk sac tumor, embryonal cell carcinoma, and mixed GCT. They originate from primordial germ cells, which become incorporated into the fetal gonads. Thus, GCTs may occur in the gonadal tissues themselves or along the path of primordial germ cell migration. In adults, GCTs occur most commonly in the gonads. In children, sacrococcygeal tumors predominate.1-4 Teratomas are a common form of GCT. They are defined histologically as containing tissues derived from all 3 germ cell layers: ectoderm, mesoderm From the aPenn State Milton S. Hershey Medical Center, Hershey, PA; b Radiology Specialists of Florida, Orlando, FL; and cMallinckrodt Institute of Radiology, Barnes-Jewish Hospital/Washington University, St. Louis, MO. Reprint requests: Christine M. Peterson, MD, Penn State Milton S. Hershey Medical Center, Hershey, PA. E-mail: [email protected]. Curr Probl Diagn Radiol 2012;41:210-219. © 2012 Mosby, Inc. All rights reserved. 0363-0188/$36.00 ⫹ 0 doi:10.1067/j.cpradiol.2012.02.001
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(most teratomas contain fat, an imaging hallmark, which is a mesodermal derivative), and endoderm. Teratomas are also classified as mature or immature, depending on the degree of differentiation of its components. In adults, immature tumors are more likely to exhibit malignant behavior. Although a soft tissue component to the mass is often seen in immature teratomas, it can be difficult to distinguish mature from immature teratomas using imaging alone. Although adjuvant chemotherapy may be used, treatment is usually surgical.1-5
Intracranial Teratomas Intracranial teratomas account for up to 50% of fetal brain tumors. In neonates, they comprise 33% of intracranial tumors but only 2%-4% of intracranial tumors in other patients ⬍15 years.6 They typically arise from the pineal gland and involve the third ventricle.6 The mass is often cystic, and the presence of calcification is highly suggestive of the diagnosis. Clinical features include polyhydramnios related to impaired fetal swallowing of amniotic fluid (Fig 1).
Head and Neck Teratomas The head and neck are common sites of teratomas in children. Tumors may originate from the thyrocervical area, palate, or nasopharynx (Figs 2 and 3). As in the cranium, tumors are usually midline and contain cystic spaces. Calcifications within the mass are very characteristic. Polyhydramnios is commonly present because of impaired swallowing.7,8 Peripartum mortality is often related to difficulty in establishing an airway after delivery; however, survivability is improved when the airway is established before the fetus is completely delivered and the placenta and umbilical cord are removed (Figs 4 –7).
Curr Probl Diagn Radiol, November/December 2012
FIG 1. Sagittal T1 (A) image shows a heterogeneously enhancing cystic and solid mass in an adult patient presenting with headache. Axial T1 (B) and sagittal contrast-enhanced T1 (C) images from a child with a similar presentation show a mass to the right of midline. The mass contains fat and cystic components with partial enhancement. Pathology showed a mature teratoma.
FIG 2. Fetal MR performed after an abnormal screening ultrasound (US) shows a complex solid and cystic mass (arrow) arising from roof of the mouth and extending into oropharynx, with most of the mass external to the mouth. Pathology demonstrated a mature teratoma. (Color version of figure is available online.)
Mediastinal Teratomas The mediastinum is an uncommon location for GCTs. Teratomas account for 75% of mediastinal GCTs and usually occur in the anterior mediastinum near the thymus. They are more commonly encountered in younger patients. Most mediastinal teratomas are of the mature subtype, with only the
Curr Probl Diagn Radiol, November/December 2012
FIG 3. T2 image in a child with a mass in the mouth shows a mixed cystic and solid mass (arrows). There is enhancement of the solid components of this mass. The mass crosses numerous spaces of the face and neck and obstructs the oral airway. Pathology revealed a mixed mature and immature teratoma. (Color version of figure is available online.)
minority containing immature elements. Immature teratomas in the mediastinum have a low malignant potential. Malignancy occurs in approximately 20% of cases and is seen almost exclusively in men.9 As seen elsewhere, cysts within the mass, as well as internal fat and calcification, are characteristic (Figs 8 and 9).
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FIG 4. T1-weighted (T1W) (A) and CT (B, C) images of a child with a protuberant mass arising from the mouth show a complex mass originating from right aspect of nasal cavity extending posteriorly into the right middle and anterior cranial fossa, as well as the suprasellar region. There is a large extrafascial exophytic component beyond the upper lip. The mass is solid and cystic and contains fat (arrow in A) and calcification (arrow in B). There is enhancement of some solid portions. Pathology showed colonic and gastric mucosa. (Color version of figure is available online.)
FIG 5. Prenatal US image (A) and postnatal images (B and C) show a large mass representing a head and neck teratoma in a child with a protuberant mass arising from the mouth (Case courtesy of Kathleen Eggli, MD). (Color version of figure is available online.)
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Curr Probl Diagn Radiol, November/December 2012
FIG 6. CT (A, B) and T1 ⫹ contrast (C) images demonstrate a mixed cystic and solid right orbital mass in a child with a protuberant eye mass. The mass contains fat and calcification and has heterogeneous contrast enhancement. It deforms and enlarges the bony orbit without cortical destruction. The tumor extends externally through the optic canal with no intracranial extension.
FIG 7. Fetal MR (A) performed after an abnormal screening US shows a complex multilocular cervical mass extending from below the glottis to the anterior superior mediastinum. Postnatal US (B) in the same patient shows a complex partially cystic mass with solid areas; it extends superiorly to the submandibular region and inferiorly to just below the aortic arch. Pathology revealed immature neural elements and respiratory epithelium, cartilage, and immature glands. (Color version of figure is available online.)
Retroperitoneal Teratomas Retroperitoneal teratomas are uncommon, accounting for fewer than 10% of all primary retroperitoneal tumors. Approximately 50% cases arise in the first decade of life. There is a majority of women, with a female-to-male ratio of 2:1 (Figs 10 –12).3-5,10 Teratomas in this location tend to be very well developed and can sometimes resemble normal fetal elements, the so-called “fetus-in-fetu” appearance.
Sacrococcygeal Teratomas FIG 8. CT performed after an abnormal chest radiograph in an adult male shows a predominantly cystic anterior mediastinal mass with some fat (arrow). Pathology demonstrated respiratory epithelium, pancreatic tissue, and entrapped thymus. (Color version of figure is available online.)
Curr Probl Diagn Radiol, November/December 2012
The sacrococcygeum is the most common location of GCTs in children. Seventy-five percent of tumors are diagnosed in the neonatal period, with most diagnosed
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FIG 9. Posteroanterior chest radiograph (PA CXR) (A) and CT (B) show an anterior mediastinal mass, which contains soft tissue and fat. Pathology demonstrated mature cystic teratoma. This mass occurred in an adult male and was incidentally discovered.
to type IV where the tumor is confined to the presacral space (Figs 15 and 16). There has been an increased attention on prenatal diagnosis. The prognosis for a fetus with sacrococcygeal teratoma is substantially worse than for a neonate with a newly diagnosed tumor, with a mortality rate of nearly 50% for fetuses diagnosed before 30 weeks’ gestation.11
Testicular Teratomas
FIG 10. US in a child shows a large, predominantly cystic retroperitoneal mass. Pathology was consistent with immature teratoma with neural tissue, bone marrow, and intestinal mucosa.
by age 4. Females are affected 4-times more often than males. Up to 27% of sacrococcygeal teratomas are malignant, with the probability of malignancy increasing as the age of the child at presentation increases. Ninety percent of these tumors are benign in children younger than 2 months, but ⬍50% benign in children older than 2 months (Figs 13 and 14).3 Sacrococcygeal teratomas are classified into 4 types, depending on the degree of internal involvement by the tumor. The classification ranges from type I in which the tumor is entirely external to the patient
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Teratomas are the second most common testicular neoplasm in children. However, in adults, pure teratomas are rare, and teratomatous elements are most commonly seen as components of mixed GCTs. Although they occur in both children and adults, their natural history contrasts sharply. In children, teratomas, whether mature or immature, behave as a benign lesion. However, during and after puberty, both the mature and immature components of testicular teratomas can metastasize and are thus considered malignant.12-14 (Fig 17). As elsewhere in the body, cystic components to the mass are fairly characteristic of teratomas, whereas other testicular neoplasms tend to be solid. The presence of calcification within the mass is also suggestive of the diagnosis (Fig 18). Malignant transformation is more common in testicular teratomas than in their ovarian counterparts, with recurrence risk of 20% in both mature and immature testicular teratomas.12-14
Curr Probl Diagn Radiol, November/December 2012
FIG 11. US (A) in an adult patient with flank pain shows a mixed echogenicity mass posterior to the right kidney. CT (B) shows the soft tissue and fat components in the right paraspinal mass. Pathology revealed a cystic teratoma.
FIG 12. CT in a child with increased abdominal girth shows a large, complex, cystic retroperitoneal mass containing fat and calcium. Pathology revealed a malignant teratoma.
FIG 13. US in a child with abnormal bowel habits shows a primarily cystic presacral mass containing thick septations. Pathology revealed neuroglial tissue, choroid plexus, respiratory epithelium, mature cartilage, and smooth muscle elements consistent with mature teratoma. (Color version of figure is available online.)
Ovarian Teratomas Ovarian teratomas consist of mature teratomas, immature teratomas, and monodermal teratomas (one tissue type predominates). A common form of monodermal teratomas is struma ovarii, where the tumor is composed mostly of mature thyroid tissue.15,16
Curr Probl Diagn Radiol, November/December 2012
Mature teratomas of the ovary, also known as dermoid cysts, account for 10%-20% of all ovarian neoplasms, with peak incidence in the third decade. In the pediatric population, they are the most common ovarian neoplasm. The presence of fat
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FIG 14. T1W (A) and T2W (B) images in a child with a visible mass demonstrate fat within the mass (arrows in A), soft tissue, and cystic components (arrows in B). T1 ⫹ C (C) image shows heterogeneous enhancement of the solid portions of the mass and its septations. Pathology revealed a mixed immature and mature teratoma with multifocal endodermal sinus tumor. (Color version of figure is available online.)
FIG 15. Fetal MR performed after an abnormal screening US (A) and postnatal CT (B) shows an exophytic, primarily solid, heterogeneously enhancing mass arising from the coccygeal region. The mass is entirely external, with no presacral components. Pathology showed immature neural tissue and presence of cartilage, respiratory mucosa, and yolk sac tumor. Surgical photograph in a different patient (C) shows the typical appearance of the lobular soft tissue mass. (Color version of figure is available online.)
FIG 16. CT in an adult patient with abdominal pain shows a complex, partially cystic mass arising from the adnexa with associated ascites. Pathology showed immature neural tubules, cartilage, pigmented iris epithelium, respiratory epithelium, and gastrointestinal mucosa.
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FIG 17. US image from a 10-month-old child with a testicular mass shows a heterogeneous, solid, and cystic mass with increased blood flow. Pathology showed keratinized epithelium surrounded by normal seminiferous tubules and immature neuronal tissue representing an immature teratoma. (Color version of figure is available online.)
Curr Probl Diagn Radiol, November/December 2012
FIG 18. (A) A 20-year-old male with a known immature teratoma arising within an undescended testicle. (B) CT shows widely metastatic disease. Note the fat density within the lesions, as well as foci of calcium (arrow in A). (Color version of figure is available online.)
FIG 19. An abdominal radiograph (A) in a woman with constipation shows an incidental cluster of toothlike calcifications in the pelvis. Calcifications are present in approximately 50% of teratomas; 31% of these recapitulate teeth. Sagittal midline US image of the pelvis (B) shows a mixed cystic and solid mass. Note the shadowing within the solid component, likely from calcification. CT (C) shows fat within the mass.
within the lesion on computed tomography (CT) or magnetic resonance imaging is the most critical diagnostic feature. Cystic spaces and calcifications are also characteristic. Rokitansky protuberances are papillary projections arising from the cyst wall and are typical of mature teratomas. They tend to contain the hair and calcium components of the mass (Figs 19 and 20). These lesions are usually asymptomatic unless complicated by torsion or, rarely, malignant degeneration. Malignant degeneration into squamous cell carcinoma may infrequently occur with a teratoma, but there is no imaging feature that is diagnostic of this complication (Fig 21).15,16 Immature teratomas tend to occur in younger women, accounting for another 5% of all ovarian tumors. It is difficult to distinguish between mature
Curr Probl Diagn Radiol, November/December 2012
and immature teratomas using imaging, but features that suggest immature components include a prominent soft tissue component of the mass with calcifications scattered throughout the lesions as opposed to contained within the Rokitansky protuberance.15,16 In summary, teratomas are a common neoplasm with a characteristic appearance. Familiarity with the typical imaging appearances of these lesions will aid the radiologist in the diagnosis of this entity. Summary Teaching Points: ●
In adults, GCTs occur most commonly in the gonads. Teratomas are a common form of germ cell tumor. They are defined histologically as containing tissues derived from all 3 germ cell layers: ectoderm, mesoderm (most teratomas contain fat, an imaging hallmark, which is a
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FIG 20. (A) CT image in a child shows an incidental fat-containing mass, with pathology showing fat, hair, and soft tissue elements. (B) Histologic analysis showed cartilage, hair follicles, skin, and choroid plexus. (Color version of figure is available online.)
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FIG 21. Fat-containing ovarian dermoid in an elderly female patient presenting with bloating. Pathologic diagnosis revealed a small focus of malignant degeneration into squamous cell carcinoma. The diagnosis of malignancy could not be made preoperatively.
mesodermal derivative), and endoderm. Teratomas are also classified as mature or immature. ● Intracranial teratomas typically arise from the pineal gland and involve the third ventricle. The mass is often cystic, and the presence of calcification is highly suggestive of the diagnosis. ● The head and neck are common sites of teratomas in children. Tumors may originate from the thyrocervical area, palate, or nasopharynx. Peripartum mortality is often related to difficulty in establishing an airway after delivery.
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The mediastinum is an uncommon location for germ cell tumors. Cysts within the mass, as well as internal fat and calcification, are characteristic. Retroperitoneal teratomas tend to be very well developed and can sometimes resemble normal fetal elements. Sacrococcygeal teratomas are classified into 4 types, depending on the degree of internal involvement by the tumor. The classification ranges from type I in which the tumor is entirely external to the patient to type IV where the tumor is confined to the presacral space. During puberty, both the mature and immature components of testicular teratomas can metastasize and are thus considered malignant. In the pediatric population, ovarian teratomas are the most common ovarian neoplasm. The presence of fat within the lesion is the most diagnostic feature. Cystic spaces and calcifications are also characteristic. These lesions are usually asymptomatic unless complicated by torsion or, rarely, malignant degeneration.
REFERENCES 1. Billmore FD. Germ cell tumors. Surg Clin North Am 2006; 86:489-503. 2. Ruvin E, Farber JL, editors. Pathology. 2nd edn. J. B. Philadelphia, PA: Lippincott, 1994. p. 889-91, 958-59. 3. Ueno T, Tanaka YO, Nagata M, et al. Spectrum of germ cell tumors: From head to toe. Radiographics 2004;24:387-404. 4. Woodward PJ, Sohaey R, Kennedy A, Koeller KK. From the archives of the AFIP: A comprehensive review of fetal tumors with pathologic correlation. Radiographics 2005;25:215-42.
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5. Chaudhary A, Misra S, Wakhlu A, et al. Retroperitoneal teratomas in children. Indian J Pediatr 2006;73:221-4. 6. Sandow BA, Dory CE, Aguiar MA, et al. Best cases from the AFIP: Congenital intracranial teratoma. Radiographics 2004; 24:1165-70. 7. Lloyd C, McHugh K. The role of radiology in head and neck tumours in children. Cancer Imaging 2010;10:49-61. 8. Vandenhaute B et al. Epignathus teratoma: Report of three cases with a review of the literature. Cleft Palate Craniofac J 2000;37:83-91. 9. Jeung M, Gasser B, Gangi A, et al. Imaging of cystic masses of the mediastinum. Radiographics 2002;22:79-93. 10. Pereira JM, Sirlin CB, Pinto PS, et al. CT and MR imaging of extrahepatic fatty masses of the abdomen and pelvis: Techniques, diagnosis, differential diagnosis, and pitfalls. Radiographics 2005;25:69-85.
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11. Kocaglu M, Frush DP. Pediatric presacral masses. Radiographics 2006;26:833-57. 12. Carver BS, Al-Ahmadie H, Sheinfeld J. Adult and pediatric testicular teratoma. Urol Clin North Am 2007;34:245-51. 13. Woodward PJ, Sohaey R, O’Donoghue MJ, et al. Tumors and tumorlike lesions of the testis: Radiologic-pathologic correlation. Radiographics 2002;22:189-216. 14. Kocakoc E, Bhatt S, Dogra V. Ultrasound evaluation of testicular neoplasms. Ultrasound Clin 2007;2:27-44. 15. Jung SE, Lee JM, Rha SE, et al. CT and MR imaging of ovarian tumors with emphasis on differential diagnosis. Radiographics 2002;22:1305-25. 16. Outwater EK, Siegelman ES, Hunt JL. Ovarian teratomas: Tumor types and imaging characteristics. Radiographics 2001; 21:475-90.
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Germ cell tumors (GCTs) may occur in both children and adults and include a broad array of histologic subtypes, such as teratoma, seminoma (known as dysgerminoma in the ovary and germinoma in the pineal gland), choriocarcinoma, yolk sac tumor, embryonal cell carcinoma, and mixed GCT. In adults, GCTs occur most commonly in the gonads. In children, sacrococcygeal tumors predominate. Teratomas are a common form of GCT. They are defined histologically as containing tissues derived from all 3 germ cell layers: ectoderm, mesoderm (most teratomas contain fat, an imaging hallmark, which is a mesodermal derivative), and endoderm. Teratomas are also classified as mature or immature, depending on the degree of differentiation of its components, and in adults, immature tumors are more likely to exhibit malignant behavior.
Germ cell tumors (GCTs) may occur in both children and adults and include a broad array of histologic subtypes, such as teratoma, seminoma (known as dysgerminoma in the ovary and germinoma in the pineal gland), choriocarcinoma, yolk sac tumor, embryonal cell carcinoma, and mixed GCT. They originate from primordial germ cells, which become incorporated into the fetal gonads. Thus, GCTs may occur in the gonadal tissues themselves or along the path of primordial germ cell migration. In adults, GCTs occur most commonly in the gonads. In children, sacrococcygeal tumors predominate.1-4 Teratomas are a common form of GCT. They are defined histologically as containing tissues derived from all 3 germ cell layers: ectoderm, mesoderm From the aPenn State Milton S. Hershey Medical Center, Hershey, PA; b Radiology Specialists of Florida, Orlando, FL; and cMallinckrodt Institute of Radiology, Barnes-Jewish Hospital/Washington University, St. Louis, MO. Reprint requests: Christine M. Peterson, MD, Penn State Milton S. Hershey Medical Center, Hershey, PA. E-mail: [email protected]. Curr Probl Diagn Radiol 2012;41:210-219. © 2012 Mosby, Inc. All rights reserved. 0363-0188/$36.00 ⫹ 0 doi:10.1067/j.cpradiol.2012.02.001
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(most teratomas contain fat, an imaging hallmark, which is a mesodermal derivative), and endoderm. Teratomas are also classified as mature or immature, depending on the degree of differentiation of its components. In adults, immature tumors are more likely to exhibit malignant behavior. Although a soft tissue component to the mass is often seen in immature teratomas, it can be difficult to distinguish mature from immature teratomas using imaging alone. Although adjuvant chemotherapy may be used, treatment is usually surgical.1-5
Intracranial Teratomas Intracranial teratomas account for up to 50% of fetal brain tumors. In neonates, they comprise 33% of intracranial tumors but only 2%-4% of intracranial tumors in other patients ⬍15 years.6 They typically arise from the pineal gland and involve the third ventricle.6 The mass is often cystic, and the presence of calcification is highly suggestive of the diagnosis. Clinical features include polyhydramnios related to impaired fetal swallowing of amniotic fluid (Fig 1).
Head and Neck Teratomas The head and neck are common sites of teratomas in children. Tumors may originate from the thyrocervical area, palate, or nasopharynx (Figs 2 and 3). As in the cranium, tumors are usually midline and contain cystic spaces. Calcifications within the mass are very characteristic. Polyhydramnios is commonly present because of impaired swallowing.7,8 Peripartum mortality is often related to difficulty in establishing an airway after delivery; however, survivability is improved when the airway is established before the fetus is completely delivered and the placenta and umbilical cord are removed (Figs 4 –7).
Curr Probl Diagn Radiol, November/December 2012
FIG 1. Sagittal T1 (A) image shows a heterogeneously enhancing cystic and solid mass in an adult patient presenting with headache. Axial T1 (B) and sagittal contrast-enhanced T1 (C) images from a child with a similar presentation show a mass to the right of midline. The mass contains fat and cystic components with partial enhancement. Pathology showed a mature teratoma.
FIG 2. Fetal MR performed after an abnormal screening ultrasound (US) shows a complex solid and cystic mass (arrow) arising from roof of the mouth and extending into oropharynx, with most of the mass external to the mouth. Pathology demonstrated a mature teratoma. (Color version of figure is available online.)
Mediastinal Teratomas The mediastinum is an uncommon location for GCTs. Teratomas account for 75% of mediastinal GCTs and usually occur in the anterior mediastinum near the thymus. They are more commonly encountered in younger patients. Most mediastinal teratomas are of the mature subtype, with only the
Curr Probl Diagn Radiol, November/December 2012
FIG 3. T2 image in a child with a mass in the mouth shows a mixed cystic and solid mass (arrows). There is enhancement of the solid components of this mass. The mass crosses numerous spaces of the face and neck and obstructs the oral airway. Pathology revealed a mixed mature and immature teratoma. (Color version of figure is available online.)
minority containing immature elements. Immature teratomas in the mediastinum have a low malignant potential. Malignancy occurs in approximately 20% of cases and is seen almost exclusively in men.9 As seen elsewhere, cysts within the mass, as well as internal fat and calcification, are characteristic (Figs 8 and 9).
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FIG 4. T1-weighted (T1W) (A) and CT (B, C) images of a child with a protuberant mass arising from the mouth show a complex mass originating from right aspect of nasal cavity extending posteriorly into the right middle and anterior cranial fossa, as well as the suprasellar region. There is a large extrafascial exophytic component beyond the upper lip. The mass is solid and cystic and contains fat (arrow in A) and calcification (arrow in B). There is enhancement of some solid portions. Pathology showed colonic and gastric mucosa. (Color version of figure is available online.)
FIG 5. Prenatal US image (A) and postnatal images (B and C) show a large mass representing a head and neck teratoma in a child with a protuberant mass arising from the mouth (Case courtesy of Kathleen Eggli, MD). (Color version of figure is available online.)
212
Curr Probl Diagn Radiol, November/December 2012
FIG 6. CT (A, B) and T1 ⫹ contrast (C) images demonstrate a mixed cystic and solid right orbital mass in a child with a protuberant eye mass. The mass contains fat and calcification and has heterogeneous contrast enhancement. It deforms and enlarges the bony orbit without cortical destruction. The tumor extends externally through the optic canal with no intracranial extension.
FIG 7. Fetal MR (A) performed after an abnormal screening US shows a complex multilocular cervical mass extending from below the glottis to the anterior superior mediastinum. Postnatal US (B) in the same patient shows a complex partially cystic mass with solid areas; it extends superiorly to the submandibular region and inferiorly to just below the aortic arch. Pathology revealed immature neural elements and respiratory epithelium, cartilage, and immature glands. (Color version of figure is available online.)
Retroperitoneal Teratomas Retroperitoneal teratomas are uncommon, accounting for fewer than 10% of all primary retroperitoneal tumors. Approximately 50% cases arise in the first decade of life. There is a majority of women, with a female-to-male ratio of 2:1 (Figs 10 –12).3-5,10 Teratomas in this location tend to be very well developed and can sometimes resemble normal fetal elements, the so-called “fetus-in-fetu” appearance.
Sacrococcygeal Teratomas FIG 8. CT performed after an abnormal chest radiograph in an adult male shows a predominantly cystic anterior mediastinal mass with some fat (arrow). Pathology demonstrated respiratory epithelium, pancreatic tissue, and entrapped thymus. (Color version of figure is available online.)
Curr Probl Diagn Radiol, November/December 2012
The sacrococcygeum is the most common location of GCTs in children. Seventy-five percent of tumors are diagnosed in the neonatal period, with most diagnosed
213
FIG 9. Posteroanterior chest radiograph (PA CXR) (A) and CT (B) show an anterior mediastinal mass, which contains soft tissue and fat. Pathology demonstrated mature cystic teratoma. This mass occurred in an adult male and was incidentally discovered.
to type IV where the tumor is confined to the presacral space (Figs 15 and 16). There has been an increased attention on prenatal diagnosis. The prognosis for a fetus with sacrococcygeal teratoma is substantially worse than for a neonate with a newly diagnosed tumor, with a mortality rate of nearly 50% for fetuses diagnosed before 30 weeks’ gestation.11
Testicular Teratomas
FIG 10. US in a child shows a large, predominantly cystic retroperitoneal mass. Pathology was consistent with immature teratoma with neural tissue, bone marrow, and intestinal mucosa.
by age 4. Females are affected 4-times more often than males. Up to 27% of sacrococcygeal teratomas are malignant, with the probability of malignancy increasing as the age of the child at presentation increases. Ninety percent of these tumors are benign in children younger than 2 months, but ⬍50% benign in children older than 2 months (Figs 13 and 14).3 Sacrococcygeal teratomas are classified into 4 types, depending on the degree of internal involvement by the tumor. The classification ranges from type I in which the tumor is entirely external to the patient
214
Teratomas are the second most common testicular neoplasm in children. However, in adults, pure teratomas are rare, and teratomatous elements are most commonly seen as components of mixed GCTs. Although they occur in both children and adults, their natural history contrasts sharply. In children, teratomas, whether mature or immature, behave as a benign lesion. However, during and after puberty, both the mature and immature components of testicular teratomas can metastasize and are thus considered malignant.12-14 (Fig 17). As elsewhere in the body, cystic components to the mass are fairly characteristic of teratomas, whereas other testicular neoplasms tend to be solid. The presence of calcification within the mass is also suggestive of the diagnosis (Fig 18). Malignant transformation is more common in testicular teratomas than in their ovarian counterparts, with recurrence risk of 20% in both mature and immature testicular teratomas.12-14
Curr Probl Diagn Radiol, November/December 2012
FIG 11. US (A) in an adult patient with flank pain shows a mixed echogenicity mass posterior to the right kidney. CT (B) shows the soft tissue and fat components in the right paraspinal mass. Pathology revealed a cystic teratoma.
FIG 12. CT in a child with increased abdominal girth shows a large, complex, cystic retroperitoneal mass containing fat and calcium. Pathology revealed a malignant teratoma.
FIG 13. US in a child with abnormal bowel habits shows a primarily cystic presacral mass containing thick septations. Pathology revealed neuroglial tissue, choroid plexus, respiratory epithelium, mature cartilage, and smooth muscle elements consistent with mature teratoma. (Color version of figure is available online.)
Ovarian Teratomas Ovarian teratomas consist of mature teratomas, immature teratomas, and monodermal teratomas (one tissue type predominates). A common form of monodermal teratomas is struma ovarii, where the tumor is composed mostly of mature thyroid tissue.15,16
Curr Probl Diagn Radiol, November/December 2012
Mature teratomas of the ovary, also known as dermoid cysts, account for 10%-20% of all ovarian neoplasms, with peak incidence in the third decade. In the pediatric population, they are the most common ovarian neoplasm. The presence of fat
215
FIG 14. T1W (A) and T2W (B) images in a child with a visible mass demonstrate fat within the mass (arrows in A), soft tissue, and cystic components (arrows in B). T1 ⫹ C (C) image shows heterogeneous enhancement of the solid portions of the mass and its septations. Pathology revealed a mixed immature and mature teratoma with multifocal endodermal sinus tumor. (Color version of figure is available online.)
FIG 15. Fetal MR performed after an abnormal screening US (A) and postnatal CT (B) shows an exophytic, primarily solid, heterogeneously enhancing mass arising from the coccygeal region. The mass is entirely external, with no presacral components. Pathology showed immature neural tissue and presence of cartilage, respiratory mucosa, and yolk sac tumor. Surgical photograph in a different patient (C) shows the typical appearance of the lobular soft tissue mass. (Color version of figure is available online.)
FIG 16. CT in an adult patient with abdominal pain shows a complex, partially cystic mass arising from the adnexa with associated ascites. Pathology showed immature neural tubules, cartilage, pigmented iris epithelium, respiratory epithelium, and gastrointestinal mucosa.
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FIG 17. US image from a 10-month-old child with a testicular mass shows a heterogeneous, solid, and cystic mass with increased blood flow. Pathology showed keratinized epithelium surrounded by normal seminiferous tubules and immature neuronal tissue representing an immature teratoma. (Color version of figure is available online.)
Curr Probl Diagn Radiol, November/December 2012
FIG 18. (A) A 20-year-old male with a known immature teratoma arising within an undescended testicle. (B) CT shows widely metastatic disease. Note the fat density within the lesions, as well as foci of calcium (arrow in A). (Color version of figure is available online.)
FIG 19. An abdominal radiograph (A) in a woman with constipation shows an incidental cluster of toothlike calcifications in the pelvis. Calcifications are present in approximately 50% of teratomas; 31% of these recapitulate teeth. Sagittal midline US image of the pelvis (B) shows a mixed cystic and solid mass. Note the shadowing within the solid component, likely from calcification. CT (C) shows fat within the mass.
within the lesion on computed tomography (CT) or magnetic resonance imaging is the most critical diagnostic feature. Cystic spaces and calcifications are also characteristic. Rokitansky protuberances are papillary projections arising from the cyst wall and are typical of mature teratomas. They tend to contain the hair and calcium components of the mass (Figs 19 and 20). These lesions are usually asymptomatic unless complicated by torsion or, rarely, malignant degeneration. Malignant degeneration into squamous cell carcinoma may infrequently occur with a teratoma, but there is no imaging feature that is diagnostic of this complication (Fig 21).15,16 Immature teratomas tend to occur in younger women, accounting for another 5% of all ovarian tumors. It is difficult to distinguish between mature
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and immature teratomas using imaging, but features that suggest immature components include a prominent soft tissue component of the mass with calcifications scattered throughout the lesions as opposed to contained within the Rokitansky protuberance.15,16 In summary, teratomas are a common neoplasm with a characteristic appearance. Familiarity with the typical imaging appearances of these lesions will aid the radiologist in the diagnosis of this entity. Summary Teaching Points: ●
In adults, GCTs occur most commonly in the gonads. Teratomas are a common form of germ cell tumor. They are defined histologically as containing tissues derived from all 3 germ cell layers: ectoderm, mesoderm (most teratomas contain fat, an imaging hallmark, which is a
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FIG 20. (A) CT image in a child shows an incidental fat-containing mass, with pathology showing fat, hair, and soft tissue elements. (B) Histologic analysis showed cartilage, hair follicles, skin, and choroid plexus. (Color version of figure is available online.)
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FIG 21. Fat-containing ovarian dermoid in an elderly female patient presenting with bloating. Pathologic diagnosis revealed a small focus of malignant degeneration into squamous cell carcinoma. The diagnosis of malignancy could not be made preoperatively.
mesodermal derivative), and endoderm. Teratomas are also classified as mature or immature. ● Intracranial teratomas typically arise from the pineal gland and involve the third ventricle. The mass is often cystic, and the presence of calcification is highly suggestive of the diagnosis. ● The head and neck are common sites of teratomas in children. Tumors may originate from the thyrocervical area, palate, or nasopharynx. Peripartum mortality is often related to difficulty in establishing an airway after delivery.
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The mediastinum is an uncommon location for germ cell tumors. Cysts within the mass, as well as internal fat and calcification, are characteristic. Retroperitoneal teratomas tend to be very well developed and can sometimes resemble normal fetal elements. Sacrococcygeal teratomas are classified into 4 types, depending on the degree of internal involvement by the tumor. The classification ranges from type I in which the tumor is entirely external to the patient to type IV where the tumor is confined to the presacral space. During puberty, both the mature and immature components of testicular teratomas can metastasize and are thus considered malignant. In the pediatric population, ovarian teratomas are the most common ovarian neoplasm. The presence of fat within the lesion is the most diagnostic feature. Cystic spaces and calcifications are also characteristic. These lesions are usually asymptomatic unless complicated by torsion or, rarely, malignant degeneration.
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