Diagnostic Ultrasound - Abdomen and Pelvis

Spermatocele/Epididymal Cyst
TERMINOLOGY
Definitions
• Spermatocele: Retention cyst of rete testis or epididymis
containing spermatozoa
• Epididymal head cyst: Collection of simple fluid
IMAGING
General Features
• Best diagnostic clue
○ Simple or minimally complex cystic mass within head of
epididymis
• Location
○ Head of epididymis
• Size
○ 3 mm to 10 cm
• Morphology
○ Epididymal head cysts are anechoic, thin walled, and
avascular
○ Spermatoceles may contain linear septations and
internal debris
Imaging Recommendations
• Best imaging tool
○ US
• Protocol advice
○ Grayscale US with color Doppler imaging
Ultrasonographic Findings
• Simple or complex cystic mass: May be multiseptated; may
contain diffuse; low-level echoes due to spermatozoa
• "Falling snow" sign: Mechanically moving particulate
material within cyst due to acoustic radiation force from
color Doppler
DIFFERENTIAL DIAGNOSIS
Hematocele
• History of trauma
• Complex fluid collection within tunica vaginalis
• Contains echogenic clot and fibrin strands
Pyocele
• Associated with epididymoorchitis with hyperemia and
enlargement of epididymis &/or testis
• Complex fluid collection located within tunica vaginalis
• Contains white-cell debris and fibrinous strands producing
linear septations and low-level echoes
Hydrocele
• Simple or complex intrascrotal fluid collection within tunica
vaginalis
Cyst of Tunica Albuginea
• Usually small (2-5 mm) simple cyst between layers of tunica
albuginea
• Associated abnormalities
○ Dilation of rete testis within mediastinum of testis
Gross Pathologic & Surgical Features
• Complex cystic mass containing simple fluid or milky fluid
and spermatozoa, depending on type
CLINICAL ISSUES
Presentation
• Most common signs/symptoms
○ Painless scrotal mass
– Rare hypofertility or torsion
○ Cystic masses can be transilluminated like hydroceles at
physical exam
Demographics
• Age
○ Any age can be affected
• Epidemiology
○ Very common; present in 20-40% of men
Treatment
• Most can be observed if asymptomatic
• Surgery (spermatocelectomy) only if sufficiently large to
cause discomfort
DIAGNOSTIC CHECKLIST
Consider
• Abscess: Correlate with recent epididymitis and ongoing
hyperemia
• Inguinal hernia: Should vary with Valsalva maneuver and
exhibit expected gut signature or echogenic fat
Image Interpretation Pearls
• Cystic mass in head of epididymis with "falling snow" sign
on color Doppler US
• Cystic extratesticular lesions almost always benign; if no
vascularized soft tissue elements, not neoplasm
SELECTED REFERENCES
1. Yang JR et al: Comparison between Open Epididymal Cystectomy and
Minimal Resection of Epididymal Cysts Using a Scrotoscope: A Clinical Trial
for the Evaluation of a New Surgical Technique. Urology. ePub, 2015
2. Erikci V et al: Management of epididymal cysts in childhood. J Pediatr Surg.
48(10):2153-6, 2013
3. Rioja J et al: Adult hydrocele and spermatocele. BJU Int. 107(11):1852-64,
2011
4. Valentino M et al: Cystic lesions and scrotal fluid collections in adults:
Ultrasound findings. J Ultrasound. 14(4):208-15, 2011
5. Posey ZQ et al: Rate and associations of epididymal cysts on pediatric scrotal
ultrasound. J Urol. 184(4 Suppl):1739-42, 2010
6. Sista AK et al: Color Doppler sonography in evaluation of spermatoceles: the
"falling snow" sign. J Ultrasound Med. 27(1):141-3, 2008
7. Smart JM et al: Ultrasound findings of masses of the paratesticular space.
Clin Radiol. 63(8):929-38, 2008
Diagnoses: Scrotum
PATHOLOGY
General Features
• Etiology
○ Scarring secondary to either epididymitis, trauma, or
vasectomy
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