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.
The 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.
- 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 appearance 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 the 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.
- testicular germ cell tumour, e.g. seminoma: tends to show vascularity
- tunica albuginea cyst: tends to be completely anechoic
- focal intratesticular granulomatous disease, e.g tuberculosis
- focal testicular haemorrhage
Ultrasound - testicular and scrotal
- ultrasound (introduction)
testicular and scrotal ultrasound
unilateral testicular lesion
- testicular torsion
- testicular rupture
- germ cell tumours of the testis
- sex cord / stromal tumours of the testis
- bilateral testicular lesion
- paratesticular lesions
- tubular ectasia of the rete testis
- cystadenoma of the rete testis
- testicular sarcoidosis
- testicular tuberculosis
- spermatic cord
- fibrous pseudotumour of the scrotum
- scrotal leiomyosarcoma
- testicular adrenal rest tumours (TARTs)
- tunica vaginalis testis mesothelioma
- splenogonadal fusion
- unilateral testicular lesion
- 1. Loya AG, Said JW, Grant EG. Epidermoid cyst of the testis: radiologic-pathologic correlation. Radiographics. 2004;24 Suppl 1 : S243-6. doi:10.1148/rg.24si035223 - Pubmed citation
- 2. Bennett GL, Garcia RA. Benign intratesticular dermoid cyst: sonographic findings. AJR Am J Roentgenol. 2002;179 (5): 1315-7. doi:10.2214/ajr.179.5.1791315 - Pubmed citation
- 3. Cho JH, Chang JC, Park BH et-al. Sonographic and MR imaging findings of testicular epidermoid cysts. AJR Am J Roentgenol. 2002;178 (3): 743-8. doi:10.2214/ajr.178.3.1780743 - Pubmed citation
- 4. Langer JE, Ramchandani P, Siegelman ES et-al. Epidermoid cysts of the testicle: sonographic and MR imaging features. AJR Am J Roentgenol. 1999;173 (5): 1295-9. doi:10.2214/ajr.173.5.10541108 - Pubmed citation
- 5. Dogra VS, Gottlieb RH, Rubens DJ et-al. Benign intratesticular cystic lesions: US features. Radiographics. 2001;21 Spec No : S273-81. Radiographics (full text) - Pubmed citation
- 6. Kim W, Rosen MA, Langer JE et-al. US MR imaging correlation in pathologic conditions of the scrotum. Radiographics. 2007;27 (5): 1239-53. doi:10.1148/rg.275065172 - Pubmed citation