Download Extratesticular epidermoid cyst mimicking enlarged testis

Ir J Med Sci
DOI 10.1007/s11845-008-0264-6
CASE REPORT
Extratesticular epidermoid cyst mimicking enlarged testis
H.-W. Kao Æ C.-J. Wu Æ M.-F. Cheng Æ W.-C. Chang Æ
C.-Y. Chen Æ G.-S. Huang
Received: 23 September 2008 / Accepted: 4 November 2008
Ó Royal Academy of Medicine in Ireland 2008
Abstract Epidermoid cysts are benign simple epithelial
tumors usually appearing as hypoechoic lesions with
scattered echogenic reflectors on sonography. Herein, we
present a 53-year-old man with an extratesticular epidermoid cyst in the right scrotum which shows confusing
sonographic findings, normal-appearing echogenicity of
the lesion and atrophied testis, which lead to a diagnostic
dilemma. With a variety of sonographic presentations in
extratesticular epidermoid cysts, magnetic resonance (MR)
imaging could play a complementary role in difficult cases.
intratesticular ones, which are the most common benign
testicular neoplasms. They usually present as hypoechoic
masses that are easily to be recognized and differentiated
from normal testes. As an exception to the general rule, the
diagnosis of our case was ambiguous until MR imaging
was performed. With this case, we stress not only the
importance of being familiar with various sonographic
presentations of epidermoid cysts, but also the crucial role
of MR imaging in challenging circumstances.
Keywords Epidermoid cyst Extratesticular Magnetic resonance imaging Sonography
Case report
Introduction
Sonography is usually the first imaging modality to
investigate scrotal disorders, and it can help differentiate
extratesticular lesions from intratesticular ones with very
high accuracy [1]. However, the differentiation may seldom be a challenge in certain situations. The extratesticular
epidermoid cysts are relatively rare, in contrast to the
H.-W. Kao C.-J. Wu (&) W.-C. Chang C.-Y. Chen G.-S. Huang
Department of Radiology, Tri-Service General Hospital
and National Defense Medical Center, 325, Cheng-Kung Rd.,
Sec. 2, Taipei 114, Taiwan, Republic of China
e-mail: [email protected]
M.-F. Cheng
Department of Pathology, Tri-Service General Hospital and
National Defense Medical Center, Taipei, Taiwan, Republic
of China
A 53-year-old man presented with a 3-year history of
painless enlargement of the right scrotum. He did not
seek medical treatment until urinary difficulty developed.
Clinical examination revealed a firm mass in the right
scrotum, while the left scrotum was normal. Gray-scale
sonography of the right scrotum showed a large solid mass
with homogeneous echogenicity similar to the contralateral
normal testis, findings initially been regarded as orchitis or
a disseminated testicular tumor (Fig. 1). MR imaging
showed a septate cyst, 9 cm in length, with homogeneous
low signal on T1-weighted images and high signal on
T2-weighted images (Fig. 2). The right testis was small
and pushed inferomedially by the cyst. A series of laboratory examination showed normal values, including alfafetoprotein and beta-human chorionic gonadotropin.
Surgical excision found a well-defined extratesticular
cystic lesion without rupture. Pathologic examination
depicted an epidermoid cyst lined by a stratified squamous
epithelium and filled with keratinous debris (Fig. 3). The
cyst showed no evidence of inflammation or infection. The
final diagnosis was extratesticular epidermoid cyst. The
patient was stable in 1-year follow-up.
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Fig. 1 Axial sonography of both testes showed similar and homogeneous echogenicity with enlargement of the right (arrow)
Discussion
Epidermoid cysts are common benign epithelial cysts.
They are well encapsulated with keratinized squamous
epithelial walls and filled with sebaceous material. The
lack of cutaneous adnexal structures, such as hair follicles
or teeth, make epidermoid cysts different from dermoid
ones [2]. They may be monolayer teratomas originating
from germ cells or result from traumatic implantation of
epidermal tissue into the dermis or subcutis. These are
usually asymptomatic, unless they become infected,
enlarged to compress adjacent structure, or rupture [3].
Extratesticular epidermoid cysts are usually subcutaneous
and frequently located at the median raphe from the distal
penis to the anus [4]. In the scrotum, they should be differentiated from other paratesticular lesions, including
cystic and solid ones such as spermatocele, complex cyst,
or rhabdomyosarcoma.
On sonography, epidermoid cysts most often appeared
as hypoechoic masses with scattered reflectors and posterior sound enhancement but no color Doppler signals.
However, the echogenicity of the cysts may vary widely
from anechoic to heterogeneous solid appearing, depending
on their content [5]. They may be ovoid, spherical, lobulated or tubular in shape. In our case, the echogenicity of
the cyst was unique in that it simulated the normal testis.
Furthermore, the large size of the cyst and the atrophic
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Fig. 2 Axial MR imaging of the scrotum demonstrated a large cystic
lesion (thick arrow) in the right scrotum with low signal and no
contrast enhancement on T1-weighted images (a) and high signal on
T2-weighted images (b). The atrophic testis (thin arrow) was pushed
inferomedially
testis hidden below made the sonographic diagnosis even
more challenging. In this circumstance, color Doppler
ultrasound may help to differentiate true solid lesions from
the solid-appearing ones by the presence of blood flow [6].
But it should be noticed that some ruptured epidermoid
cysts also have color Doppler signals inside [5]. Ultimately, the sonographic findings are not specific and
surgical exploration is required.
MR imaging, in some situations like ours, may provide
more supportive findings of epidermoid cyst [3]. It typically appears as a well-defined mass with low signal on
T1-weighted images and high signal on T2-weighted
images. There may be low-signal-intensity foci in the cyst,
representing keratin debris, and no contrast enhancement.
Furthermore, MR imaging can depict the atrophic testis
which may be missed on sonography. In our case, the
valuable information of MR imaging did lead to correct
preoperative diagnosis which helps a lot in treatment and
surgical planning.
In conclusion, we presented a pitfall of sonography in
diagnosing and extratesticular epidermoid cyst, and stressed the value of MR imaging in this clinical dilemma.
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Fig. 3 Bilobed specimen showed a well-capsulated lesion with white
keratin content (a). Pathologic examination (b, H&E, 9100) depicted
a typical picture of epidermoid cyst with stratified squamous
epithelial walls (thick arrow) and keratin (thin arrow)
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