Epidermoid Cyst

The testicular ultrasound reveals a 1 x 10 x 0.9 cm. right upper pole testicular mass with a small cystic component (Figure 1). Two concentric echogenic lines are seen just periperal to the cystic area, and no internal flow is detected in the mass. This was felt to be consistent with epidermoid cyst vs. germ cell neoplasia. The mass was excised by partial orchiectomy through a right inguinal approach. It was found to be a 1 cm. well circumscribed round mass with a flaky, yellow grumous center, characteristic of an epidermoid cyst.

Epidermoid cysts account for 1% of testicular tumors and usually present between the 2nd and 4th decades of life.¹ They are typically round, hard, well circumscribed and encapsulated intratesticular masses which have a yellow, claylike center on cut section. Because of the early age of presentation and an occasional association with cryptorchidism, epidermoid cysts are thought to represent a monolayer form of teratoma. While coexistence with other germ cell tumor elements can only be excluded by microscopic evaluation, the clinical behavior of these tumors tends to be benign. Ultrasound demonstration of a well circumscribed lesion with a central solid core can aid in distinguishing an epidermoid cyst from a germ cell tumor. Many advocate radical orchiectomy as the only definitive way to rule out malignancy. However, local excision in selected patients appears to be equally effective.²

References

Shah KH, Maxted WC, and Chun B. Epidermoid cysts of the Testis. Cancer. 47:577, 1981.
Richie JP. Neoplasms of the testis: Campell's Urology, 6th ed. Walsh PC et al (editors). Saunders, 1992.

Michael Kearney is a fourth year medical student at Boston University Medical School