Epidermoid cyst of the testis

Epidermoid cyst of the testis is a rare benign lesion of the testis. It is important to differentiate it from a testicular teratoma.

Epidermoid cyst of the testis
Diagnosis in short
LM	unilocular cyst lined by squamous epithelium without significant nuclear atypia, no ITGCN
LM DDx	teratoma, mixed germ cell tumour, immature teratoma, dermoid cyst of testis (subtype of teratoma)
Gross	unilocular cyst containing keratineous material with a laminated appearance
Grossing notes	orchiectomy grossing
Site	testis
Signs	testicular mass
Symptoms	typically asymptomatic
Prevalence	rare (1-2% of testicular masses)
Blood work	normal (beta-hCG, AFP, LDH)
Prognosis	benign
Clin. DDx	other testicular mass - germ cell tumours, abscess
Treatment	excision to exclude a malignant tumour/treat symptoms

General

• Rare.
• Benign.
• 1-2% of testicular tumours.
• Typical age: teens to thirties (range: 3-77).

Clinical:

• Asymptomatic mass (typical).

Gross

Features:

• Unilocular cyst containing keratineous material with a laminated appearance.

Notes:

• Teratomas are usually multilocular.
• Presence of hair suggests a dermoid cyst.

Microscopic

Features:

• Cyst lined by squamous epithelium without significant nuclear atypia.
• No adnexal structures.
• No intratubular germ cell neoplasia in the adjacent seminiferous tubules.
• No nuclear atypia.

Notes:

• Surround testis usually within normal limits.
• Granulomas may be seen in the context of cyst rupture.

DDx:

• Dermoid cyst - adnexal structures, e.g. sweat glands, hair follicules.
• Teratoma - nuclear atypia, multilocular, mesenchyme elements, ITGCN present.
• Mixed germ cell tumour.

See also

• Testis.