CASE OF THE WEEK
2020-25 / June 22
(Contributor: Daniel H Russell)
A man in his mid 30s presented with a testicular mass. Areas represented by the photomicrograph encompassed several low magnification fields. A minor percentage of seminoma was present, while the majority of the lesion was teratoma. WT1 was expressed by lesional tissue shown.
Quiz
1. What is the diagnosis?
a. Mixed Germ Cell Tumor, Seminoma and Teratoma
b. Yolk Sac Tumor
c. Primitive Neuroectodermal Tumor (PNET)
d. Well Differentiated Neuroendocrine Tumor (Carcinoid Tumor)
e. Mixed Germ Cell Tumor, Seminoma and Teratoma, with Somatic-Type Malignancy
1. e
1. Mixed Germ Cell Tumor, Seminoma and Teratoma, with Somatic Type Malignancy
Somatic-type malignancy (STM) occurs in approximately 3% of all patients with germ cell tumors of the testis, including approximately 23% of all patients with recurrence. The diagnosis of STM carries prognostic implications, as 80% of STM metastases recur and the 5 year cancer specific survival of patients with STM approximates 64%, well below those without STM. Histologically, the diagnosis requires uninterrupted somatic tumor encompassing a minimum of 5 mm (for non-carcinomas), while carcinomas require the presence of infiltrative, destructive tumor invasion. Focal areas of immature somatic tissues, typically adjacent to teratoma, should not be diagnosed as STM. The most common STM histotype is rhabdomyosarcoma, although many others have been described including PNET, Wilm’s Tumor, lineage specific adenocarcinomas, and leiomyosarcomas, to name a few. The most common germ cell tumor associated with STM is teratoma. Many cases occur in the post-treatment setting, while some are occult. In the latter, the diagnosis can be treacherous, and the presence of any midline cancer in males under the age of 40 should raise suspicion for primary or metastatic germ cell tumor. Midline sarcomas should be distinguished from sarcomatoid YST, common in the post-chemotherapy setting, and STM sarcomas, while midline glandular tumors should be distinguished from glandular predominant YST and STM adenocarcinomas. In this setting immunohistochemistry with glypican-3, AFP, EMA, and keratins can be useful, as co-expression of glypican-3 or AFP with EMA or keratins is diagnostic of YST. A potential pitfall includes the acquiring of lineage-specific immunophenotypic expression by STM components. In such a scenario, FISH for i12p or 12p amplification can be of considerable benefit in confirming the origin from germ cell cancer in tumors of post-pubertal incipience
1. Magers MJ, Kao CS, Cole CD, Rice KR, Foster RS, Einhorn LH, Ulbright TM. “Somatic-type” malignancies arising from testicular germ cell tumors: a clinicopathologic study of 124 cases with emphasis on glandular tumors supporting frequent yolk sac tumor origin. Am J Surg Pathol. 2014 Oct;38(10):1396-1409.
2. Malagón HD, Valdez AM, Moran CA, Suster S. Germ cell tumors with sarcomatous components: a clinicopathologic and immunohistochemical study of 46 cases. Am J Surg Pathol. 2007 Sep;31(9):1356-1362.
3. Colecchia M, Necchi A, Paolini B, Nicolai N, Salvioni R. Teratoma with somatic-type malignant components in germ cell tumors of the testis: a clinicopathologic analysis of 40 cases with outcome correlation. Int J Surg Pathol. 2011 Jun;19(3) 321-327.
Daniel H. Russell
Tripler Army Medical Center
russdanny22@gmail.com
The contributor acknowledges Dr. Thomas Raj for taking the photomicrographs for this case.
Testis
Somatic Type Malignancy, Teratoma, Sarcomatoid Yolk Sac Tumor, Recurrent Germ Cell Tumor, Glandular Yolk Sac Tumor