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AJR Integrative Imaging LIFELONG LEARNING FOR RADIOLOGY |
1 Section of Abdominal Imaging, Imaging Institute, Cleveland Clinic, 9500 Euclid
Ave. – A21, Cleveland, OH 44195.
2 Present address: Department of Radiology, University of California San
Francisco, San Francisco, CA 94143.
Received March 15, 2007; accepted after revision May 25, 2007.
Address correspondence to E. M. Remer
(remere1{at}ccf.org).
Objective
We discuss five scenarios in which sonography is useful for diagnosing scrotal abnormalities, including painful scrotal disorders, an incidental disorder, and scrotal masses. Practice questions are included for your review.
Conclusion
Sonography is the primary diagnostic tool for diagnosing disorders in the scrotum.
Keywords: infection • neoplasm • sonography • testicle • torsion
INTRODUCTION
Sonography is the primary imaging modality used to diagnose disorders of the scrotum and its contents. It is advocated as the most appropriate study in the setting of acute scrotal pain in patients without trauma [1]. Neoplastic, inflam matory, congenital, and vascular abnormalities are detected with high sensitivity and sonographic findings are key to guiding clinical management.
EDUCATIONAL OBJECTIVES
By completing this educational activity, the participant will:
Scenario 1
Clinical History
A 17-year-old boy presents with acute onset of left scrotal pain
approximately 10 hours earlier. On physical examination, the left scrotum is
diffusely tender and mildly ery thematous.
Description of Images
Gray-scale sonography shows markedly heterogeneous echotexture of the left
testis (Fig. 1A). By
comparison, the echogenicity of the right testis is normal
(Fig. 1B). Color Doppler
sonography shows no intratesticular flow and minimal flow surrounding the left
testis (Fig. 2).
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| PRACTICE QUESTION 1 What is your preferred diagnosis?
PRACTICE QUESTION 2 Which sonographic feature is most specific for acute testicular torsion?
PRACTICE QUESTION 3 Which of the following is TRUE regarding segmental testicular infarction?
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Solution to Practice Question 1
Acute epididymitis is usually the result of descending infection often
caused by urinary tract pathogens. In young men, it most commonly results from
gonococcus or Chlamydia organisms. If epididymitis involves the
testis (epididymoorchitis), sonography will frequently show an enlarged,
heterogeneous, predominantly hypoechoic testis with increased color flow.
Option A is not the best response. The absence of flow in the affected testis
shown on color and spectral Doppler sonography is a highly sensitive and
specific finding in acute testicular torsion. Option B is the best
response. Although patients with segmental testicular infarction usually
present with an acute scrotum, sonography typically shows a wedge-shaped,
hypoechoic region of absent flow with otherwise normal testicular parenchyma.
Option C is not the best response. Although tumors can be difficult to
distinguish from benign entities, testicular tumors are an uncommon cause of
acute scrotal pain. Most large and infiltrative tumors are hypervascular.
Option D is not the best response.
Solution to Practice Question 2
In torsion, the testis becomes enlarged and heterogeneous within the first
6 hours. Heterogeneous echotexture, however, is a common finding in sonograms
for evaluation of acute scrotal pain regardless of cause. Option A is not the
best response. Testicular enlargement (option C) and hydrocele (option D) are
frequent, but nonspecific, findings in patients with testicular torsion.
Unilateral absent flow is the most accurate sign of acute testicular torsion.
Keep in mind, however, that intermittent or incomplete torsion may result in
false-negative studies. Option B is the best response.
Solution to Practice Question 3
Segmental testicular infarction is an ischemic process observed on
sonography as a focal, rounded, or wedge-shaped avascular area, most often in
the upper or middle portion of the testis
(Fig. 2). Option A is not the
best response. Differentiation from a small, hypovascular, intratesticular
tumor on sonography is difficult, and in many cases the diagnosis is made
after orchiectomy. Option B is not the best response. MRI may prove helpful to
make a more specific preoperative diagnosis
[2]. Although no clear cause
has been determined, the proposed mechanism is torsion and detorsion of the
testis producing ischemia in the upper pole of the testis, a region with an
inconstant collateral arterial supply. Option C is not the best response. The
list of conditions associated with segmental testicular infarction is long and
includes acute epididymoorchitis, polycythemia, sickle cell disease,
hypersensitivity angiitis, Wegener's granulomatosis, and pelvic surgery,
especially herniorrhaphy. Option D is the best response
[3].
Conclusion
The diagnosis in this patient is acute testicular torsion. Color Doppler
sonography is instrumental in differentiating torsion from other causes of
acute scrotal pain. Unilateral absent or diminished flow is the most accurate
sign of torsion. Although some peripheral blood flow can be seen in the torsed
testis, the presence of central flow is a strong negative predictor. The
gray-scale sonographic appearance of torsion varies with time. The testis
becomes enlarged and inhomogeneous within the first 6 hours, and heterogeneity
worsens in the subacute phase (6 hours–5 days). Worsening degree of
heterogeneity appears to correspond to loss of viability
[4]. Hydrocele and scrotal skin
thickening are usually present but are nonspecific. The degree of torsion can
be variable, ranging from 180° to 720°. Lesser degrees of torsion may
produce incomplete occlusion of blood flow and lead to chronic ischemia.
Torsion of the testicular appendages (appendix testis or appendix epididymis)
occurs predominantly in boys 7–14 years old and can mimic testicular
torsion clinically. The torsed appendix is seen on sonography as a round
extratesticular mass with high or mixed echogenicity and no Doppler flow.
Blood flow in the testes, however, is normal, although paratesticular
hyperemia may be seen.
Scenario 2
Clinical History
A 61-year-old man presents with scrotal swelling and pain of 2 days'
duration. Onset of the pain followed heavy lifting. Gray-scale sonography and
Doppler sonography of the scrotum are performed.
Description of Images
Gray-scale sonography shows marked epididymal enlargement
(Fig. 3A), hypoechogenicity,
and hydrocele (Fig. 3B). Color
Doppler sonography shows increased color flow (hyperemia) in the epididymis
and testis (Fig. 3C).
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| PRACTICE QUESTION 4 Which sonographic feature is most sensitive for scrotal inflammation?
PRACTICE QUESTION 5 In the United States, what is the most common causative organism in acute epididymoorchitis in men older than 50 years?
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Solution to Practice Question 4
The hallmark of scrotal inflammation is hyperemia of the epididymis,
testis, or both on color Doppler sonography. The sensitivity of color Doppler
sonography for scrotal inflammation is close to 100%. Furthermore, in 20% of
patients with epididymitis and 40% of patients with orchitis, gray-scale
sonography is normal and hyperemia may be the only finding
[5]. Option D is the best
response. Scrotal skin thickening, reactive hydrocele, and increased
epididymal echotexture are frequent, but nonspecific, findings in patients
with acute scrotal pain. Options A, B, and C are not the best responses.
Epididymal enlargement can be seen in torsion, trauma, epididymitis, and
infiltrative processes such as leukemia and lymphoma. Option E is not the best
response.
Solution to Practice Question 5
Approximately 2–4% of tuberculous infections involve the genitals;
however, epididymal tuberculosis is uncommon in the United States
[6]. Option A is not the best
response. Infectious epididymoorchitis is usually the result of descending
infection caused by urinary tract pathogens, most commonly Escherichia
coli. Option B is the best response. In young adults, scrotal
infection usually results from sexually transmitted diseases. Options C and D
are not the best responses. Pseudomonas organisms, Proteus
mirabilis, and Klebsiella organisms are less common urinary
tract pathogens and less common causes of epididymitis. Option E is not the
best response.
Conclusion
The diagnosis in this patient is acute epididymo-orchitis. Infectious
epididymitis commonly involves the epididymal head but may involve the entire
epididymis in up to 50% of cases. Involvement of the adjacent testis occurs in
20–40% of cases and can be focal or diffuse. Although hyperemia allows
differentiation from complete torsion, trauma can cause enlargement and
hyperemia in the absence of infection. Granulomatous diseases such as
tuberculosis, brucellosis, and sarcoidosis are less common causes of
epididymitis and orchitis. Orchitis without epididymitis is typical of
infection by the paramyxovirus causing mumps. Mumps orchitis may be bilateral
in up to 35% of cases. Lymphoma involving the testis can be difficult to
distinguish from epididymoorchitis on the basis of sonographic features alone.
Like epididymoorchitis, lymphoma causes hypoechoic enlargement of the testis
and epididymis with hyperemia; however, lymphoma is typically painless and
will not resolve with interval antibiotic treatment.
Scenario 3
Clinical History
A 37-year-old man presents with scrotal pain after testicular trauma.
Description of Images
Multiple punctate, nonshadowing, echogenic foci are noted on sonography of
the right testis (Fig. 4). No
intratesticular mass is seen.
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| PRACTICE QUESTION 6 In the entity demonstrated in Scenario 3, the punctate, echogenic foci in the testes are:
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Solution to Practice Question 6
The typical distribution of this entity is diffuse and bilateral. Option A
is not the best response. Several reports have shown concomitant intratubular
germ cell neoplasia and microcalcifications in the same testis
[7]. However, the
calcifications themselves are not germ cell neoplasia. Although there is
direct evidence of an increased risk of concurrent malignancy in the setting
of intratubular germ cell neoplasia, the subsequent development of germ cell
neoplasm in patients with isolated testicular microlithiasis is less well
established [8]. Option B is
not the best response. Microlithiasis is often discovered incidentally on
sonography obtained for scrotal pain or trauma; however, the condition is
neither painful nor associated with trauma. Options C and D are not the best
responses. Histologically, the punctate bright echoes in testicular
microlithiasis are laminated calcium deposits in the lumen of the seminiferous
tubules [9]. Option A is the
best response.
| PRACTICE QUESTION 7 Which of the following is NOT a current management recommendation for patients with testicular microlithiasis?
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Solution to Practice Question 7
A lack of consensus exists regarding the preferred follow-up of
microlithiasis in patients without a concurrent neoplasm, and thus many
differing recommendations can be found in the literature and in practice
[10]. Most authors agree that
at least an annual physical examination and scrotal sonography are prudent.
Options A and B are not the best responses. Others have gone further,
advocating testicular biopsy to detect concurrent premalignant intratubular
germ cell neoplasia. Option C is not the best response. Because the relative
risk of concurrent neoplasm in a patient with testicular microlithiasis has
been reported to be as high as 21.6-fold
[11], some experts recommend
screening CT of the chest, abdomen, and pelvis when microlithiasis is
detected. Option D is not the best response. The latter two recommendations
remain controversial. Unlike prophylactic mastectomy in high-risk women,
prophylactic orchiectomy has not been advocated in the literature. Option E
is the best response.
Conclusion
The diagnosis in this patient is testicular microlithiasis, which is
defined as five or more punctuate echogenic foci in a single transducer field.
A wide variation is seen in the reported prevalence of testicular
microlithiasis, ranging from 0.68% to 18.1%. Although testicular
microlithiasis is clearly associated with concurrent neoplasm, significant
controversy exists about the risk that it leads to the subsequent development
of neoplasm [8,
12]. No real differential
exists for microcalcifications. Clustered intratesticular macrocalcifications
(>3 mm) can be seen in so-called burned-out germ cell tumors or Sertoli
cell tumors and may be seen after trauma.
Scenario 4
Clinical History
A 28-year-old man presents with a nontender, palpable right testicular
mass.
Description of Images
Gray-scale sonography shows a well-circumscribed mass in the testis with
hyperechogenic rim and heterogeneous, predominantly sonolucent center
(Fig. 5). Some acoustic
shadowing is observed. No laminations are identified.
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| PRACTICE QUESTION 8 Sonography of a nontender, palpable testicular mass in a young adult man shows a well-circumscribed mass in the testis with alternating hyperechoic and hypoechoic rings. Which of the following is the most likely diagnosis?
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Conclusion
The diagnosis in this patient is intratesticular epidermoid cyst. Several
embryologic origins of this lesion have been postulated, including squamous
metaplasia of the rete testis, epidermal inclusion, or monodermal development
of a teratoma [15]. The main
internal component of the epidermoid cyst is keratin. The variable sonographic
appearance probably reflects the evolution of the lesion, with successive
layers of keratin and desquamated epithelium creating the laminated
appearance. In masses without classic sonographic findings, epidermoid cysts
may be mistaken for malignancy. Treatment has been controversial, but most
sources now agree that excisional biopsy and biopsy of the adjacent parenchyma
to rule out intratubular germ cell neoplasia can be undertaken in men with
negative tumor markers and characteristic sonographic findings. Other benign
testicular "masses" include tunica albuginea cysts, tubular
ectasia of the rete testis, abscess, hematoma, adrenal rests, and segmental
infarction.
Scenario 5
Clinical History
A 37-year-old man presents with a painless, firm lump adjacent to the left
testis.
Description of Images
Gray-scale sonography shows a mixed-echogenicity mass adjacent to the left
testis in the expected position of the epididymis
(Fig. 6).
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| PRACTICE QUESTION 9 Which of the following is TRUE regarding extratesticular scrotal masses?
PRACTICE QUESTION 10 Which of the following is the most common tumor involving the spermatic cord?
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Solution to Practice Question 9
In contrast to testicular masses, most extratesticular scrotal masses are
benign [16]. Cystic scrotal
masses are especially likely to be benign. Option A is not the best response.
Supernumerary testes are rare, usually presenting as a painless, scrotal mass.
Twenty percent of supernumerary testes are inguinal. Option B is not the best
response. Papillary cystadenoma, a benign tumor of the epididymis, has a
strong association with von Hippel-Lindau (VHL) disease. Bilateral epididymal
cystadenomas are virtually pathognomonic for VHL. Option B is the best
response. Adenomatoid tumor is the most common epididymal tumor; however,
lipomas, which usually occur in the spermatic cord, are the most common
extratesticular scrotal tumor
[16]. Option D is not the best
response.
| PRACTICE QUESTION 11 Which of the following is TRUE regarding adenomatoid tumors of the scrotum?
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Solution to Practice Question 10
Lipomas are the most common extratesticular scrotal tumor, arising most
often in the spermatic cord. Option D is the best response. They
account for approximately half of all cord tumors. Other benign tumors of the
cord include leiomyoma, lymphangioma, and dermoid, but these are much less
common. Option A is not the best response. Rhabdomyosarcoma and liposarcoma
are the most common sarcomas of the scrotum, usually arising from the mesoderm
of the spermatic cord [16].
Rhabdomyosarcomas occur predominantly in children and often present with
retroperitoneal adenopathy and distant metastasis. Option B is not the best
response. Lymphoma involving the epididymis or spermatic cord without
testicular involvement is extremely rare. Option C is not the best response.
Adenomatoid tumors involve the epididymis. Option E is not the best
response.
Solution to Practice Question 11
Adenomatoid tumors of the epididymis account for approximately 30% of
paratesticular neoplasms. They are invariably benign. Option A is not the best
response. Although adenomatoid tumors can occur anywhere in the epididymis,
they most often arise in the epididymal tail. Option B is not the best
response. Intratesticular extension can be seen, in which case it can be
indistinguishable from germ cell tumor. Option C is the best response.
Most adenomatoid tumors are diagnosed in men between the ages of 20 and 50
years. Option D is not the best response.
Conclusion
Adenomatoid tumors are benign neoplasms of mesothelial origin that account
for nearly 30% of all paratesticular tumors; they are commonly found near the
lower pole of the testis [17].
The sonographic appearance of adenomatoid tumor of the epididymis is extremely
variable, although they are typically homogeneously hyperechoic. Tumors
predominantly arise in the epididymis, where they can be characterized as
extratesticular. About 14% arise from the testicular tunica. Origin from the
deep layer of the tunica vaginalis testis or the tunica albuginea may lead to
intratesticular growth that may make differentiation from germ cell tumor
impossible. MRI findings are useful in suggesting that the mass arises from
the tunical surface of the testis rather than from the peripheral seminiferous
tubules [18]. Other benign
tumors of the epididymis include leiomyomas and papillary cystadenomas.
Lipomas, hematomas, and hernias are common benign masses of the spermatic
cord.
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  J. W. Stengel and E. M. Remer Sonography of the Scrotum: Self-Assessment Module Am. J. Roentgenol., June 1, 2008; 190(6_Supplement): S42 - S45. [Abstract] [Full Text] [PDF]
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| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
