Diagnostic Ultrasound - Abdomen and Pelvis

Spermatocele/Epididymal Cyst
Diagnoses: Scrotum
TERMINOLOGY
• Spermatocele: Retention cyst of rete testis or epididymis
containing spermatozoa
• Epididymal head cyst: Collection of simple fluid
IMAGING
• Protocol advice: Grayscale US with color Doppler imaging
• US 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
PATHOLOGY
• Etiology: Unknown, may reflect scarring secondary to either
epididymitis, trauma, or vasectomy
KEY FACTS
• Associated abnormalities: Dilation of rete testis within
mediastinum of testis
CLINICAL ISSUES
• Most common signs/symptoms: Painless scrotal mass
○ Rare hypofertility or torsion
• Treatment: Most can be observed if asymptomatic
○ Surgery (spermatocelectomy) only if sufficiently large to
cause discomfort
DIAGNOSTIC CHECKLIST
• Image interpretation pearls: Cystic mass in head of
epididymis, either simple or with "falling snow" sign on
color Doppler US
• Cystic extratesticular lesions almost always benign; if no
vascularized soft tissue elements, not neoplasm
(Left) Typical appearance of
an incidentally discovered and
clinically unimportant
epididymal cyst is shown. Note
the well-circumscribed,
anechoic, avascular lesion
in the epididymal head. (Right)
Large epididymal cyst
(calipers) is shown with a
single thin septation in the
right hemiscrotum, displacing
the testis st inferiorly. Note
that the abdominal probe
rather than the high-frequency
linear probe was needed to
capture this large lesion.
(Left) Large spermatocele
superior to right testis
contains punctate low-level
echoes with corresponding
Doppler artifact ſt. These
punctate foci were mobile in
real time. (Right) Longitudinal
grayscale ultrasound
demonstrates a complex,
multiseptate cystic mass with
numerous locules containing
debris ſt, characteristic
findings for a spermatocele.
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