AJR 2002; 179:1315-1317
© American Roentgen Ray Society
Benign Intratesticular Dermoid Cyst: Sonographic Findings
Genevieve L. Bennett1 and
Roberto A. Garcia2
1 Department of Radiology, New York University—Bellevue Hospital Medical
Center, 560 First Ave., Tisch Hospital Rm. HW202, New York, NY 10016.
2 Department of Pathology, New York University—Bellevue Hospital Medical
Center, New York, NY 10016.
Received December 24, 2001;
accepted after revision February 28, 2002.
Address correspondence to G. L. Bennett.
Introduction
We describe the sonographic findings in a case of a pathologically
confirmed intratesticular dermoid cyst, a rare benign intratesticular mass,
and compare these sonographic findings with those of the relatively more
common epidermoid cyst.
Case Reports
An otherwise healthy 51-year-old man presented to the urology clinic at our
institution with a 2-year history of an enlarging right scrotal mass. Physical
examination revealed an enlarged right testicle, and the patient was referred
for sonographic evaluation. Both gray-scale and color Doppler sonography of
the scrotum were performed using high-resolution linear (10-MHz) and curved
linear (4-6-MHz) transducers (HDI 5000; ATL, Bothell, WA). The examination
showed a large well-circumscribed hypoechoic mass that had almost completely
replaced the right testicle; a small rim of peripheral testicular tissue was
preserved (Fig. 1A). The mass
appeared solid with no significant posterior acoustic enhancement. No
vascularity was observed within the mass on either color Doppler or power
Doppler sonography. The echotexture was relatively homogeneous with low-level
echoes and a few linear echogenic foci scattered throughout the mass
(Fig. 1B). Test results for
tumor markers were negative. The patient underwent an orchiectomy, and
pathologic examination revealed a well-circumscribed cystic lesion that was
filled with friable, tannish gray material. The lesion had replaced almost the
entire testicular parenchyma (Fig.
1C). Microscopically, the lesion had a keratinized squamous
epithelial lining and was filled with loose keratin. Focally, small tubular
glands with eccrine appearance were associated with the epithelial lining
(Fig. 1D). The lesion was
diagnosed as a dermoid cyst.
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Fig. 1A. —51-year-old man with intratesticular dermoid cyst. Sagittal
sonogram of right testicle shows 4.0 x 3.5 cm well-circumscribed solid
hypoechoic mass that almost completely replaces testicle, with thin rim of
preserved testicular tissue.
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Fig. 1B. —51-year-old man with intratesticular dermoid cyst.
High-resolution sonogram shows mass containing uniform low-level echoes and
scattered linear echogenic foci. Color Doppler and power Doppler sonography
(not shown) showed no internal vascularity.
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Fig. 1C. —51-year-old man with intratesticular dermoid cyst. Photograph
of gross pathologic specimen shows that testicular parenchyma has been
replaced by cystic lesion filled with friable, tannish gray material.
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Fig. 1D. —51-year-old man with intratesticular dermoid cyst.
Photomicrograph of histopathologic specimen shows keratinized squamous
epithelial lining and loose keratin-filled (k) lesion. Small tubular glands
within epithelial lining (arrow) have eccrine appearance.
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Our comparison case is that of a 23-year-old man who presented to the
urology clinic with a painless, palpable mass in the left testicle. On
sonography (using 10-MHz linear transducer with HDI 5000; ATL), a
well-circumscribed mass measuring 2.0 x 1.5 cm was seen in the mid to
lower pole of the left testicle. The mass appeared solid with concentric rings
of increased and decreased echogenicity, yielding an onionskin appearance
(Fig. 2A). Several punctate
echogenic foci were noted centrally, representing small calcifications. No
vascularity was found on color Doppler or power Doppler sonography. Test
results for tumor markers were negative. The sonographic appearance was
thought to be most compatible with that of an epidermoid cyst. Because of the
size of the mass and its central location in the testicle, an orchiectomy was
performed. Pathologic examination revealed a well-circumscribed cystic lesion
containing soft, tannish yellow material with a concentric pattern
(Fig. 2B). Microscopically, the
cyst lining was composed of keratinized squamous epithelium with a conspicuous
granular layer. No adnexal structures (hair follicles or sebaceous or eccrine
glands) were found. The cavity was filled with keratin that had noticeable
concentric lamination and focal microcalcification. The final diagnosis was
benign epidermoid cyst.
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Fig. 2A. —23-year-old man with intratesticular epidermoid cyst.
Sagittal sonogram of the left testicle shows well-circumscribed, heterogeneous
mass at mid to lower pole, measuring 2.0 x 1.5 cm. Concentric rings of
increased and decreased echogenicity yield laminated, onionskin appearance.
Central echogenic foci are noted that were confirmed at pathology as
calcifications. No vascularity was shown on color Doppler or power Doppler
sonography (not shown).
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Fig. 2B. —23-year-old man with intratesticular epidermoid cyst.
Photograph of gross pathologic specimen shows well-circumscribed cystic lesion
containing soft, tannish yellow material. Concentric pattern is visualized
that, at microscopic evaluation (not shown), corresponded to keratin with
concentric lamination.
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Discussion
Most intratesticular masses are malignant; however, several types of benign
lesions may be visualized on sonography, one of which is the epidermoid cyst.
The epidermoid cyst accounts for fewer than 1% of all testicular neoplasms and
usually presents clinically as a palpable, firm, nontender mass, most
frequently in patients who are in the third decade of life
[1]. Histologically, this
benign tumor is lined with squamous epithelium and contains desquamated
keratinized epithelium and keratinous debris
[2]. The sonographic features
of these lesions have been previously described
[3,4,5].
Epidermoid cysts are well circumscribed and show variable internal
echotexture. The cysts may be anechoic or hypoechoic or may have concentric
rings of hypo- and hyper-echogenicity that represent layers of keratinous
debris, yielding a laminated or onionskin appearance, as seen in our patient.
Calcification may be visualized in the lesion or in the rim. No internal
vascularity is observed on color Doppler or power Doppler sonography. These
sonographic findings should suggest the diagnosis of epidermoid cyst.
Preoperative recognition of these lesions is important. If at surgery such a
lesion can be enucleated and the diagnosis confirmed from a frozen section,
testicle-sparing surgery, rather than an orchiectomy, can be performed
[1,
6].
Dermoid cysts are less common than epidermoid cysts, with only scattered
case reports in the urology literature
[6,7,8].
These cysts can occur both within the testicle and within the scrotum
separately from the testicle. Differing histologically from epidermoid cysts,
dermoid cysts contain cutaneous appendages such as hair follicles and
sebaceous and eccrine glands
[2]. Both kinds of lesions
contain only ectodermal derivatives, which distinguishes them from teratomas,
which consist of derivatives of more than one of the embryonic germ cell
layers: ectoderm, mesoderm, or endoderm. In all reported cases of testicular
dermoid cysts, local excision, enucleation, or orchiectomy has been curative,
with no patient developing a metastatic germ cell tumor.
To our knowledge, ours is the first case report on the sonographic
appearance of a pathologically proven intratesticular dermoid cyst. Some
imaging features were similar to those of the epidermoid cyst. The dermoid
mass was well circumscribed and hypoechoic compared with the normal testicle
and had no internal vascularity at color Doppler or power Doppler sonographic
evaluation. However, the lesion was hypoechoic with uniform, low-level echoes,
unlike the laminated appearance of the epidermoid cyst. Fine linear echogenic
foci were scattered throughout the mass, which may represent desquamated
crystals of keratin and cholesterol because no calcifications were observed at
pathology. Without the characteristic laminated appearance, the dermoid cyst
is difficult to distinguish from a solid malignancy, such as a germ cell
tumor. In the correct clinical setting, other differential diagnostic
considerations might include an intratesticular hematoma or abscess. Lack of
vascularity may suggest the possibility of a complex cystic abnormality rather
than a solid lesion, although this finding is not always reliable (low
velocity flow may not be detectable). MR imaging could be helpful in
differentiating these lesions from solid masses by showing the failure of the
dermoid cysts to enhance after gadolinium administration.
In conclusion, our case report presents examples of two benign
intratesticular masses, the rare dermoid cyst and the somewhat more frequently
encountered epidermoid cyst. The laminated appearance of an epidermoid cyst is
a characteristic finding of the entity on sonography and should suggest this
diagnosis. The dermoid cyst is more uniformly hypoechoic with fine linear
echoes and could be difficult to distinguish from a solid neoplasm. However,
if the clinical setting is appropriate and test results for tumor markers are
negative, the presence of one of these benign lesions could reasonably be
suspected, and testicle-sparing surgery may be appropriate.
References
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Testicular epidermoid cysts: sonographic features with histopathologic
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J Urol
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Introduction
Case Reports
