Epidermoid Cyst of the Testis

January 1, 2003

A 25-year-old man sought evaluation of a painless, palpable, left testicular mass that had been present for more than 1 year. There was no personal or family history of cryptorchidism or malignancy. A circumscribed mass was palpated within the anterior superior pole of the left testis.

A 25-year-old man sought evaluation of a painless, palpable, left testicular mass that had been present for more than 1 year. There was no personal or family history of cryptorchidism or malignancy. A circumscribed mass was palpated within the anterior superior pole of the left testis. Initial laboratory test results were within normal limits. An ultrasonogram revealed a 1.6 X 1.2 X 1.2-cm cystic structure with alternating hypoechogenicity and hyperechogenicity (A) that strongly suggested an epidermoid cyst; however, a carcinoma could not be ruled out. A period of monitoring with ultrasonographic examinations was observed for several months. This patient subsequently underwent a partial orchiectomy; although a benign cyst was suspected, the surgeon opted for this procedure to exclude intratubular germ cell neoplasia. Pathologic examination revealed a well-circumscribed, white-tan, laminated lesion within unremarkable, red-brown testicular parenchyma (B). The largest dimension of the mass measured 1.6 cm. Microscopic examination confirmed the diagnosis of a benign epidermoid cyst. Drs Joseph Anderson and Nathan C. Birch of Omaha report that epidermoid cysts comprise 1% of testicular masses.1 These well-circumscribed, solid masses, which most often occur in the second to fourth decades of life, are not associated with distant metastases or local recurrence.1-3 The cyst is composed of a fibrous wall lined with squamous epithelium and filled with keratin debris. The layering of this debris imparts the classic “onion skin” or “target” appearance on an ultrasonogram.4 The differential diagnosis includes a dermoid cyst, mature teratoma, and germ cell neoplasm.5 Germ cell tumor can be ruled out by histologic examination. Preoperative ultrasonographic evaluation that strongly suggests an epidermoid cyst can direct the therapeutic course toward lesion enucleation, which is a more conservative treatment than a radical orchiectomy. The patient’s recovery was uneventful and complete.