Teratoma is a germ cell tumor containing mature or immature tissue components derived from two or three germ layers (ectoderm, mesoderm, endoderm). Testicular teratomas exhibit different biological behavior as prepubertal and postpubertal — prepubertal teratomas are benign, while postpubertal teratomas have malignant potential. On ultrasonography, a characteristic heterogeneous structure with coexisting cystic areas, solid components, and calcifications is seen. Serum tumor markers (AFP, beta-HCG) are usually normal in pure teratoma. It is resistant to chemotherapy and treatment is surgery.
Age Range
15-40
Peak Age
25
Gender
Male predominant
Prevalence
Uncommon
Teratoma is a neoplasm resulting from somatic differentiation of germ cells, containing tissue components derived from two or three embryonal germ layers. Mature teratoma contains well-differentiated, adult-type tissues (cartilage, bone, skin, hair, teeth, neural tissue, glandular epithelium), while immature teratoma contains fetal-type immature tissues (neuroepithelial tubules, immature cartilage). Postpubertal testicular teratomas develop on a background of GCNIS and have malignant potential — they carry metastatic potential regardless of stage. The characteristic ultrasonographic appearance results from different acoustic properties of these multiple tissue types — cartilage and bone as calcifications, sebaceous material as cystic areas, and soft tissue as solid components. Growing teratoma syndrome is the paradoxical growth of the teratoma component when viable malignant component is eliminated after chemotherapy.
The triple combination of coexisting cystic areas, solid components, and calcifications on ultrasonography is highly typical for teratoma. This triad reflects the tumor's different tissue components derived from multiple germ layers. Diagnostic confidence is further increased when T1 hyperintense areas showing signal loss on fat suppression on MRI are added.
Teratoma appears as a complex heterogeneous mass with coexisting cystic areas, solid components, and calcifications on ultrasonography. Cystic areas may contain sebaceous or mucinous material with variable echogenicity (completely anechoic or with internal echoes). Calcifications may be coarse or fine, potentially creating acoustic shadowing. Solid components are of variable echogenicity and may contain cartilaginous, osseous, or glandular tissues. This triple combination is highly typical for teratoma.
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A complex heterogeneous mass containing coexisting cystic areas, solid components, and calcifications is seen in the testicular parenchyma, consistent with teratoma.
Color Doppler ultrasonography shows limited vascularity in the solid components of teratoma. Cystic areas and calcific components are completely avascular. Vascularity is distinctly less dense than in seminoma or embryonal carcinoma. Vascularity may be minimal in mature teratoma but more prominent in immature teratoma. Unlike epidermoid cyst, it is not completely avascular.
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Color Doppler examination shows limited vascularity in solid components of the mass, with avascular appearance of cystic areas.
On T2-weighted MRI, teratoma demonstrates heterogeneous signal. Cystic components show high T2 signal, solid soft tissue components intermediate signal, and calcifications and bone components very low signal. Fat-containing areas show intermediate-to-high T2 signal. Cartilage tissue characteristically shows high signal on T2. This heterogeneous signal mosaic reflects teratoma's multiple tissue components and demonstrates MRI's superiority in tissue characterization.
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The testicular mass demonstrates heterogeneous signal on T2-weighted sequences with high-signal cystic areas, intermediate-signal solid components, and low-signal calcific areas consistent with teratoma.
On T1-weighted MRI, fat-containing components of teratoma (sebaceous material, dermoid tissue) show T1 hyperintense signal. On fat-suppressed sequences, these areas show signal loss — this finding confirms fat presence and is highly specific for teratoma diagnosis. Cystic-mucinous areas show low signal on T1, while proteinaceous cystic areas may show mild T1 hyperintensity. Calcifications appear hypointense on T1 as well.
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Hyperintense areas are seen within the mass on T1-weighted sequences showing signal loss on fat-suppressed sequences, with fat component consistent with teratoma.
On DWI, teratoma shows variable diffusion pattern. Mild-to-moderate diffusion restriction may be seen in solid cellular components of mature teratoma. Cystic and fatty areas do not show restriction. More prominent restriction may be seen in proliferative immature tissue components of immature teratoma. ADC values are heterogeneous and vary according to tissue composition. DWI may help in maturity assessment.
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The mass shows variable diffusion pattern on DWI with mild restriction in solid areas and no restriction in cystic areas.
On CT, teratoma appears as a complex mass with coexisting different tissue densities. Fat density (-20 to -100 HU) and calcifications (>200 HU) are characteristic and strongly support teratoma diagnosis. Cystic areas are seen at fluid density (0-20 HU), solid components at soft tissue density (30-60 HU). CT is important for staging — retroperitoneal cystic-solid mass (metastatic teratoma) may be identified.
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The testicular mass contains areas of fat density and calcifications on CT, consistent with teratoma.
Criteria
Composed entirely of well-differentiated, adult-type tissue components. Benign in prepubertal cases, malignant potential in postpubertal cases. Chemoresistant, complete surgical resection is curative.
Distinct Features
Well-organized cystic-solid structure with smooth margins on ultrasonography. Prominent calcifications, minimal vascularity in solid components. Signal loss on fat suppression frequently seen on MRI.
Criteria
Contains fetal-type immature tissue components (especially neuroepithelial tubules). Grading based on amount of immature neuroepithelial tissue (Grade 1-3). Malignant behavior and metastasis risk increase with degree of immaturity.
Distinct Features
More heterogeneous on ultrasonography, solid component may be dominant. More prominent restriction in immature areas on DWI. More prominent vascularity in solid components on Doppler. Calcifications may be less prominent than in mature teratoma.
Criteria
Rare. Development of somatic-type malignant tissue within teratoma (rhabdomyosarcoma, adenocarcinoma, primitive neuroectodermal tumor, leukemia, etc.). Poor prognosis. Resistant to germ cell tumor chemotherapy, requires chemotherapy specific to the somatic malignancy.
Distinct Features
Cannot be reliably distinguished from standard teratoma on imaging. Rapid growth or paradoxical growth of residual mass after chemotherapy may provide clues. Diagnosis made by surgical resection and histopathology.
Distinguishing Feature
Epidermoid cyst is characterized by 'onion ring' or 'target' pattern and is completely avascular. Teratoma has more complex structure with vascularity in solid components and contains calcifications. Tumor markers are normal in epidermoid cyst.
Distinguishing Feature
Mixed NSGCT contains more aggressive solid components (embryonal carcinoma) than teratoma, with more prominent hemorrhage and necrosis areas. AFP and beta-HCG are normal in pure teratoma; one or both elevated in NSGCT. More prominent vascularity is seen on Doppler in NSGCT.
Distinguishing Feature
Seminoma appears as a homogeneous hypoechoic mass without cystic component or calcification. Teratoma is characterized by heterogeneous structure with cystic + solid + calcification triad. Seminoma shows marked hypervascularity while teratoma has limited vascularity.
Distinguishing Feature
Burned-out GCT is typically seen as a small, calcified scar lesion. Unlike teratoma, it does not show organized cystic-solid structure. May present with retroperitoneal mass or elevated tumor markers.
Urgency
moderateManagement
Radical inguinal orchiectomy. Teratoma is chemoresistant — surgical resection is the primary treatment. Post-chemotherapy residual masses with normalized markers should be surgically resected (RPLND) as they frequently contain teratoma. Growing teratoma syndrome requires surgical intervention.Biopsy
Not NeededFollow-up
CT surveillance for retroperitoneal and distant disease. AFP and beta-HCG monitoring (should be normal in pure teratoma). Post-chemotherapy residual mass monitoring critical — growing mass with normal markers suggests growing teratoma syndrome.Teratoma is chemoresistant and the cornerstone of treatment is surgery. Testis-sparing surgery (enucleation) may be considered in prepubertal cases, while radical inguinal orchiectomy is standard in postpubertal cases. Post-chemotherapy residual masses frequently contain teratoma and require surgical resection. Growing teratoma syndrome — growing residual mass with normal tumor markers — requires urgent surgery. Somatic-type malignancy is a rare but aggressive complication.
Mature teratoma in prepubertal children has a benign course and testis-sparing surgery (enucleation) may be performed. In postpubertal males, all teratomas are considered malignant — since they are chemotherapy-resistant, surgical resection is the primary treatment. The teratoma component of mixed germ cell tumor may persist as residual mass after chemotherapy and may grow (growing teratoma syndrome). Tumor markers may be normal in pure teratoma — negative markers do not exclude malignancy.