Key Clinical Message
Testicular tumor markers are negative in patients with epidermoid cysts.
Clear margins and sole and small testicular tumors (25 mm or less)
suggest the possibility of epidermoid cyst.
Keywords: epidermoid cyst, testicular tumor, ultrasonography
Written informed consent was obtained from the patient to publish this
report in accordance with the journal’s patient consent policy.
Introduction
Testicular epidermoid cysts are rare tumors that occur in approximately
1% of testicular tumors and are often found in young men 10–39 years
of age.1–4 They are benign tumors that are often
misdiagnosed as malignant lesions in clinical practice. Although a
preoperative diagnosis can avoid unnecessary orchiectomy, it is often
difficult to achieve. Therefore, high inguinal orchiectomy is performed
in >80% of the reported cases.1Notifying the possibility of a benign tumor (1%) to patients is crucial
before surgery. We summarized specific preoperative findings
differentiating epidermoid cysts from malignant lesions. Herein, we
report six rare cases of epidermoid cysts in the testes.
Case presentation
We encountered six patients with epidermoid cysts at our hospital
between April 2010 and March 2022 (Table 1). The median age (range) was
20 (9–30) years. The tumors occurred in the right testes in two
patients and the left in the other four patients. The chief complaints
were scrotal induration in five patients and pruritus in the scrotum in
one patient. The patients had no family or medical history of testicular
cancer. Their blood counts, biochemical test results, and levels of
testicular tumor markers (lactate dehydrogenase, alpha-fetoprotein,
human chorionic gonadotropin, and human chorionic gonadotropin-β) were
within the normal ranges. Ultrasonography (US) was performed in all
patients (Figure 1). The median tumor size (range) was 17.5 (12–22) mm.
Well-defined, clear rims were observed in five patients. Since we did
not rule out malignant testicular tumors, we performed high inguinal
orchiectomy in all patients. All tumors were macroscopically
well-defined, white-toned masses (Figure 2). Microscopically, they were
cysts with thin fibrous capsules. The inner surface of each cyst was
covered with stratified squamous epithelium, and the inside was filled
with keratinized substances (Figure 3). There were no skin appendages or
other tissue components inside the cyst. All patients were diagnosed
with testicular epidermoid cysts.
Discussion
Testicular epidermoid cysts, first reported by Dockerty et al. in 1942,
are benign tumors that account for 1% of all testicular
tumors.1 They commonly affect patients 10–39 years of
age, which was almost similar to the susceptible age of having germ cell
tumors (between 20 and 39 years). Epidermoid cysts are classified as
prepubertal teratoma, but we have to realize that they frequently occur
in adulthood.2,5 Price et al. reported that 87% of
all testicular epidermoid cysts were small tumors of <30 mm in
size.2 According to the 2016 WHO classification,
epidermoid cysts are classified as prepubertal teratomas unrelated to
germ cell neoplasia in situ (GCNIS). Postpubertal teratomas are
considered malignant because they are derived from GCNIS. Contrarily,
prepubertal teratomas arise from normal primordial embryos which makes
them, including epidermoid cysts, benign lesions.6
More than 70% of pediatric testicular tumors are benign; therefore,
testicular-sparing surgery is often performed.7 The
prerequisites for the tumor to be considered benign prior to
testicular-sparing surgery are particular US findings (cystic lesions
with clear borders and calcified contents) and AFP negativity. In
addition, it is necessary to confirm that there are no malignant
findings on intraoperative frozen section examination
(FSE).8,9 We encountered one pediatric patient, but
because the boundary was relatively ill-defined on US findings (Figure
1C), high inguinal orchiectomy was performed, considering the risk of
malignant dissemination after tumor enucleation alone.
Testicular epidermoid cysts are recognized as benign tumors, and there
have been no reports of their metastasis. A report of 69 cases of
testicular epidermoid cysts worldwide showed no metastases or death from
this disease during the 1-month to 24-year observation
periods.1 In the present report, no recurrence was
observed during the observation period of 2 weeks to 3 years.
Testicular tumor markers were negative in patients with epidermoid
cysts. Previous studies have also indicated that 80% of small tumors
(less than 20–25 mm, regardless of age) are benign, and small-sized
tumors are a predictor of benign tumors.10–12 In this
study, all patients were negative for tumor markers, and their tumors
were within 25 mm in size.
US is highly useful for making preoperative diagnoses. Typically, the
outer edge has a hyperechoic partition, called an echogenic rim. A
low-echo level concentric ring (represented as an onion ring or a bull’s
eye) is seen inside when the alternating layers of compressed keratin
and exfoliated squamous epithelial cells are regular. However, when the
layers are randomly arranged with a slightly alternating pattern, the
lesion looks like a heterogeneous mass and can present varied findings.
Reflecting the internal keratinization, it is avascular in Doppler
US.13,14 In five of our six patients, hyperechoic
septa were confirmed on the outer edges and well-defined tumors were
visualized.
For histological diagnosis, Price et al. reported four diagnostic
criteria: first, the cyst wall exists in the parenchyma of the testis;
second, the inside contains layers of keratinized and non-structural
substances; third, the cyst wall surrounds the stratified squamous
epithelium; and fourth, an epidermoid cyst is defined as having no
teratoma-like tissues or skin appendages consisting of fibrous
connective tissues.2
Recently, testicular-sparing surgery has begun to be recognized to avoid
the overtreatment of benign lesions and preserve sexual functions.
According to the European Association of Urology clinical guidelines
(2022), high inguinal orchiectomy without intraoperative FSE should not
be performed in patients with suspected benign testicular
tumors.15 Fankhauser et al. reported the accuracy of
intraoperative FSE for testicular tumors.16 Axel et
al. performed testicular-sparing surgeries in 18 patients with
testicular epidermoid cysts. All patients were accurately diagnosed as
having epidermoid cysts by FSE.4
Conclusion
In this study, we reported six cases of rare testicular epidermoid
cysts. When encountering patients with negative tumor markers, clear
margins, negative Doppler flow, and sole small testicular tumors (≤25
mm), we should always consider the possibility of benign epidermoid
cysts to avoid overtreatment.