Diagnostic Ultrasound - Abdomen and Pelvis

Focal Testicular Mass
Differential Diagnoses: Scrotum
DIFFERENTIAL DIAGNOSIS
Common
• Testicular Carcinoma
• Orchitis (Epididymoorchitis)
• Testicular Torsion/Infarction
• Testicular Hematoma
Less Common
• Testicular Abscess
• Testicular Lymphoma, Leukemia, and Metastases
• Gonadal Stromal Tumor
• Testicular Epidermoid Cyst
• Testicular Adrenal Rests
• Testicular Sarcoid
ESSENTIAL INFORMATION
Key Differential Diagnosis Issues
• Correlate ultrasound with age and clinical features
• Sonographic findings are key but overlap among various
tumors
• Histopathological correlation needed
Helpful Clues for Common Diagnoses
• Testicular Carcinoma
○ Best diagnostic clue: Discrete hypoechoic or mixed
echogenicity testicular mass, ± vascularity
– Tumor ≤ 1.5 cm is commonly hypovascular
– Tumor > 1.5 cm is more often hypervascular
– Discrete mass on grayscale ultrasound with abnormal
intrinsic vascularity on color Doppler should raise
suspicion of testicular carcinoma
○ Seminoma
– Most common neoplasm in males 15-39 years old
– Well-defined, lobulated, hypoechoic, solid lesion
without calcification
– May undergo necrosis and appear partly cystic (rare)
○ Teratoma/teratocarcinoma
– Heterogeneous, complex, solid-cystic mass
– Calcification (cartilage, immature bone) ± fibrosis
characterizes teratoma/teratocarcinoma
○ Embryonal cell carcinoma
– Heterogeneous, predominantly solid, mixed
echogenicity mass
– Poorly marginated; 1/3 have cystic necrosis
– May invade tunica albuginea and distort testicular
contour
○ Choriocarcinoma
– Mixed echogenicity, heterogeneous mass
– Cystic areas and calcification common
– Hemorrhage with focal necrosis is typical feature of
choriocarcinoma
– May invade tunica albuginea
– Early hematogenous spread, especially to brain
• Orchitis (Epididymoorchitis)
○ Primarily involves epididymis
– Orchitis is usually secondary, occurring in 20-40% of
cases with epididymitis due to contiguous spread of
infection
– Primary orchitis is typically viral (mumps) and bilateral
○ Orchitis is characterized by inflammation, edema, and
hyperemia of testis
– Diffuse orchitis: Testis is diffusely enlarged with
heterogeneous echo pattern
– Focal orchitis: Hypoechoic focal area, usually adjacent
to inflamed epididymis
□ Can be differentiated from neoplasm by
demonstrating resolution on interval follow-up
– Associated with other findings of epididymoorchitis
including skin thickening, hydrocele, or pyocele
○ Increase in vascularity on color Doppler without
displacement of vessels
• Testicular Torsion/Infarction
○ Findings of torsion vary with duration and degree of cord
rotations
– Grayscale appearance in early torsion may be normal
– Decreased abnormal flow or absent flow on color
Doppler (always compare to contralateral normal side)
– Diffusely hypoechoic small testis/focal mass in
infarcted testis
– Hyperechoic regions (hemorrhage, fibrosis)
○ Segmental infarction may be sequela of inflammatory
process (orchitis) or surgical complication (hernia repair)
– Focal infarctions may be round or wedge shaped or
may have linear striated appearance
○ Infarction may occur in patients with hypercoagulable
states or advanced atherosclerosis, such as diabetes, or
as a sequela of epididymoorchitis or funiculitis
• Testicular Hematoma
○ History of scrotal trauma is present in majority of cases
○ Abnormal testicular parenchymal echogenicity
– Echogenicity depends on age of hematoma
○ Discrete linear or irregular fracture plane within testis
○ May or may not be associated with ruptured tunica
albuginea
○ Color Doppler
– Hematoma forms avascular mass within testis
– Distorted intratesticular vascularity with interruption
of vessels in area of hematoma or injury
○ Spontaneous testicular hemorrhage is rare entity where
intratesticular hemorrhage has no identifiable risk
factors
– Mixed echogenicity solid or cystic mass with lack of
significant internal color Doppler flow signals
– Changes in appearance, as clot resolution occurs over
time
Helpful Clues for Less Common Diagnoses
• Testicular Abscess
○ Epididymal abscess (6%)
○ Testicular abscess (6%)
○ Microabscess formation is usually seen in low-grade
infections (e.g., tuberculosis)
– Also seen in immunocompromised hosts
○ Well-defined, discrete, round, hypoechoic lesion(s) in
testicular parenchyma
○ Necrotic center shows no vascularity on color Doppler
studies
• Testicular Lymphoma, Leukemia, and Metastases
○ Lymphoma
1014