2020-2 / JANUARY 13

A 31 year-old male was treated with chemotherapy for clinical retroperitoneal metastases a malignant germ cell tumor composed of 90% embryonal carcinoma, 9% yolk sac tumor (YST), and 1% teratoma. Post chemotherapy there was residual retroperitoneal tumor. A retroperitoneal lymph node dissection was performed.


1. What is the correct diagnosis?

a. Metastatic embryonal carcinoma

b. Metastatic mature teratoma

c. Somatic malignant arising in a teratoma

d. Metastatic glandular and sarcomatoid yolk sac tumor

1. Metastatic glandular and sarcomatoid yolk sac tumor

There was extensive necrosis in the dissection consistent with necrotic tumor. There were scattered glands in dense fibrous tissue. These glands had prominent subnuclear vacuoles and lacked smooth muscle cuffing, which are typical features of glandular yolk sac tumor (YST). These glands were positive for Glypican 3 and alpha feto protein (AFP) and negative for EMA verifying YST. In addition, the stroma had spindle cells with hyperchromatic pleomorphic nuclei. These cells were positive for pancytokeratin, AFP, and Glypican 3 consistent with a sarcomatoid YST component. “Sarcomas” in patients with testicular germ cell tumors are a common form of “somatic-type malignancy.” There is support, based on morphology and immunohistochemistry, that many such sarcomatous tumors represent an unusual form of YST. sarcomatous differentiation of YST demonstrates 12p alterations that can be identified by interphase fluorescent in situ hybridization. Apart from 12p overrepresentation, these tumors may exhibit loss of 12p or even gain of an entire chromosome 12 (trisomy 12). Increase in 12p copy number of a sarcomatous neoplasm provides support for sarcomatoid YST in clinically ambiguous settings. All sarcomatoid YSTs occur after chemotherapy, as in this case. These tumors typically occur several years after diagnosis and behave aggressively.

Idrees MT, Ulbright TM, Epstein JI. Fluorescent In Situ Hybridization Analysis for 12p Alterations in Sarcomatoid Yolk Sac Tumors.
Am J Surg Pathol. 2019 [Epub ahead of print]
Howitt BE1, Magers MJ, Rice KR, Cole CD, Ulbright TM. Many postchemotherapy sarcomatous tumors in patients with testicular germ cell tumors are sarcomatoid yolk sac tumors: a study of 33 cases.
Am J Surg Pathol. 2015 Feb;39:251-9.

Jonathan Epstein
Johns Hopkins Hospital


Yolk sac tumor, sarcomatoid