Clinical History
A 22-year-old male presented with a palpable, painless right testicular mass.
Imaging Findings
The patient presented after there was a minor blunt injury to his penis. On physical examination, a firm, painless nodule was palpated in the right testis. There were no clinical signs of
inflammation, and the patient was referred for an ultrasound examination.
Discussion
Epidermoid cysts (EC) are thought to be benign tumours that are rarely located in the testes. They are lined with keratinising, stratified, squamous epithelium supported by fibrous tissue. They
contain only keratohyaline material and no skin appendages, in contrast to dermoids. They are usually found in men who are 20–30 years of age and may be found in singles or multiples. On
ultrasound, EC appear as round, mainly hypoechoic testicular lesions with sharp borders, and often, a lamellar configuration with concentric rings or lines of alternating echogenicity ("onion ring
sign") is seen. This is attributed to layers of keratin debris with varying densities. Sometimes, a round echogenic focus is present in the centre ("target" sign). Nevertheless, the ultrasonographic
image may be atypical, because the texture and the density of the cyst contents are variable. Calcification of the mass may also be a feature to be noted. Due to the absence of vascularity, no
signals are detected on colour doppler imaging. The differential diagnosis of a complex cystic testicular lesion should include other cystic neoplasms (mainly teratomas, which may be malignant), as
well as abscesses and haematomas of the testicle. The imaging findings that support the preoperative diagnosis of EC give substantial information to avoid performing an unnecessary orchiectomy.
Differential Diagnosis List
Epidermoid cysts of the testis.
Final Diagnosis
Epidermoid cysts of the testis.
