Diagnostic Ultrasound - Abdomen and Pelvis

Testicular Germ Cell Tumors
TERMINOLOGY
Abbreviations
• Germ cell tumor (GCT)
• Mixed germ cell tumor (MGCT)
Definitions
• Malignant germ cell tumor of testis
IMAGING
General Features
• Best diagnostic clue
○ Discrete hypoechoic or mixed echogenic testicular mass,
± vascularity
• Morphology
○ Most common neoplasm in males between ages 15-34
years
○ Mostly unilateral; contralateral tumor develops
eventually in 8%
○ Seminoma is most common pure germ cell tumor of
testis
– Bilateral in 1-3%, almost always asynchronous
Ultrasonographic Findings
• Grayscale ultrasound
○ Seminoma
– Typically well-defined, homogeneously hypoechoic,
solid mass without calcification or tunica invasion
□ With high-resolution US some lesions show a
heterogeneous echo pattern, ± lobulation
– May be solitary or multifocal masses
– May very rarely undergo necrosis and appear partly
cystic
○ Teratoma/teratocarcinoma
– Well-defined, anechoic/complex heterogeneous cystic
mass
– Cystic areas, calcification (cartilage, immature bone) ±
fibrosis characterize teratoma/teratocarcinoma
○ Embryonal cell carcinoma
– Heterogeneous, predominantly solid mass, of mixed
echogenicity
– Poorly marginated, 1/3 have cystic necrosis
– Coarse calcification infrequently seen
– Embryonal cell carcinoma are aggressive tumors, may
invade tunica albuginea and distort testicular contour
○ Yolk sac tumor
– Most common testicular neoplasm in pediatric
population
– Seen in pure form in children, while almost always
admixed with other germ cell elements in adults
○ Choriocarcinoma
– Mixed echogenicity, heterogeneous mass
– Cystic areas with calcification common
– Hemorrhage with focal necrosis is typical feature of
choriocarcinoma
– Usually rare in pure form; occurs with mixed GCT in 8%
– Highly malignant
• Color Doppler
○ Tumor < 1.5 cm is commonly hypovascular, and tumors >
1.6 cm are more often hypervascular
○ Disorganized flow is typical
○ Cystic areas are avascular
CT Findings
• CECT
○ Useful for staging retroperitoneal, nodal, and pulmonary
metastases
○ Low-attenuation nodes
○ Even nodes < 1 cm suspicious if located in typical
drainage areas; left renal hilus and right retrocaval in
location
○ Helpful to identify retroperitoneal recurrence &/or
"growing teratoma" syndrome
MR Findings
• T2WI
○ Useful for identifying nodal metastases
○ Moderate high signal intensity lymphadenopathy in
retroperitoneum
○ Seminoma is multinodular, hypointense
○ Intratumoral low signal band-like structures representing
fibrovascular septa
Nuclear Medicine Findings
• PET
○ Helpful to reduce false-negative CT study
– May aid in differentiating residual tumor from scar in
treated patients
Imaging Recommendations
• Best imaging tool
○ US to identify and characterize scrotal mass; CT or MR for
metastatic staging; PET to evaluate post-treatment
residual masses
• Protocol advice
○ High-frequency (9-15 MHz) linear array transducer
DIFFERENTIAL DIAGNOSIS
Epidermoid Cyst
• Cystic cavity lined by stratified squamous epithelium
• "Onion skin" appearance due to alternating layers of keratin
and desquamated squamous cells
• May have calcified rim, no enhancement on MR
Lymphoma
• Older age group, most common tumor of testes in men >
60 years
• 50% of cases bilateral, often multiple lesions, associated
with lymphadenopathy masses elsewhere
• Hypoechoic and hypervascular on color Doppler
Subacute Hematoma
• History of trauma, associated hematocele
• Hypoechoic on US
Segmental Infarct
• Acute pain, no palpable mass
• Infarct is typically hypoechoic, focal avascular area on color
Doppler
Focal Orchitis
• Irregular hypoechoic area within testis, enlarged epididymis
Diagnoses: Scrotum
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