Contributed by Lei Chen, MD, PhD
Published on line in September, 2004
A 3-month-old male infant with pain over the left scrotum for two days. The mother noticed bluish discoloration of the left scrotum and took the patient to the hospital. Ultrasound of the scrotum revealed no flow to the left testis and flow to the right testis. Physical examination revealed hard and enlarged left testis, 2 cm, tender to palpation. The right testis and the penis were normal in appearance. Lab test showed normal AFP level.
The specimen consists of a 2.3 x 1.5 x 1.5 cm testicle with epididymis, appendix testis and spermatic cord. The entire specimen weighs 5.0 g. Cut surface of the testis shows a bulging, white-light tan tumor surrounded by a thin rim of tan-pink testicular tissue and tunica (Fig. 1). The tumor measures 1.7 x 1.4 x 1.4 cm. It is a circumscribed, white, homogeneous soft mass with a centrally located, 0.2 cm in greatest dimension, cavity that contained straw yellow, clear fluid. The testicular tissue surrounding the tumor measures between 0.5 cm and 0.1 cm in thickness, and the mass appears to involve the rete testis. The epididymis does not appear to be grossly involved.
Sections show testis within which is a tumor composed of solid, cellular zones admixed with follicle-like, cystic structures filled with watery, faintly mucicarminophilic fluid. Some solid areas display prominent hyalinized, collagenous stroma (Figs. 2, 3, 4, and 5). The tumor cells are predominantly arranged in sheets separated by coarse fibrous trabeculae. However, in some foci, the tumor cells form smaller aggregates or nests, with a layer of palisading cells at the periphery (Fig. 6). The tumor cells are round to ovoid with poorly defined cell borders, scant to moderate amounts of finely vacuolated, amphophilic cytoplasm, and generally round to ovoid to slightly irregular nuclei with finely granular chromatin and inconspicuous to focally prominent nucleoli (Fig. 7). Mitoses are numerous (Fig. 8).
The tumor cells are immunoreactive for vimentin (Fig. 9) and inhibin (Fig. 10), and negative for wide spectrum cytokeratin (Fig. 11), epithelial membrane antigen, AFP, placental alkaline phosphatase, myogenin, Myo D1 and desmin. The controls for all special stains are adequate.