Epidermoid Cyst of the 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.