Testicular epidermoid cyst

Testicular epidermoid cysts (also known as keratocysts) are rare benign tumours of germ-cell origin that occur in the testis


Testicular epidermoid cysts account for around 1-2% of all testicular masses and typically present in mid-adulthood (2nd to 4th decades) 1,2. They are the most common type of benign testicular neoplasms6.

Clinical presentation

Presentation can be similar to those of malignant germ cell tumours. Patients typically present with a painless and non-tender, testicular mass between 1-3 cm in diameter.


Composed of layers of keratinous debris lined with keratinising squamous epithelium.

Radiographic features

  • nonvascular, relatively well-defined intratesticular mass
  • may demonstrate a characteristic lamellated "onion skin" or "whorled" appearance with alternating hyperechoic, hypoechoic rings. 
  • some lesions may show a target appearence with a halo of hypoechogenicity and a central hyperechoic region.

Tend to be well demarcated.  

  • T1: overall signal can be variable; may show alternating rings of high and low signal
  • T2: may a low intensity rim 3; may also show alternating rings of high and low signal
  • T1 C+ (Gd): typically no contrast enhancement 3

Treatment and prognosis

These lesions are benign with no malignant potential 3.

If the diagnosis of an epidermoid is suspected at preoperative US, the lesion can be enucleated and frozen sections obtained to confirm the diagnosis. However, treatment is controversial; some authorities advocate orchiectomy, others suggest organ sparing surgery. 

Differential diagnosis

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