A solid and microcystic pattern, similar to that in the gonadal counterpart, was seen in a large portion of the tumor.
Multiple Schiller-Duval bodies are present. They almost look like glomeruli in the kidneys, with a globular aggregate of cells projecting into a luminal space.
Areas of necrosis can be seen.
Focal nuclear atypia and mitoses are also present.
Schiller-Duval bodies and hyaline globules (bright pink blobs) are plentiful.
Strong immunoreactivity for AFP is typical.
Overall, teratomas are the most common mediastinal tumor (44%), followed by seminomas (37%). Yolk sac tumor (YST) is the most common pure nonseminomatous germ cell tumor of the mediastinum.1
Mediastinal germ cell tumors (GCT) occur more commonly in adolescents and early middle aged individuals (15-35). In the very young patient, congenital teratomas and yolk sac tumors account for almost all cases. In the older patient, all types of GCTs may be found. Interestingly, patients with Klinefelter syndrome demonstrate an increased incidence of extragonadal germ cell tumors, and in particular those in the mediastinum.
Microscopically, YST displays the same wide range of morphologies as that of its testicular counterpart. Some of the more common patterns include microcystic, endodermal-sinus pattern with the formation of Schiller-Duval bodies, parietal pattern with redundant basal-lamina formation and hepatoid pattern with solid sheets of eosinophilic cells. Eosinophilic globules of AFP may also be found. These tumors should demonstrate immunoreactivity for AFP. For more information about yolk sac tumors of the testes, please visit our case for that entity. See link below.
Usually affects young men. May present with chest pain, shortness of breath, or superior vena cava syndrome due to obstruction by the tumor.
No clear cut therapy, but surgery with chemotherapy seems to be somewhat more beneficial than surgery alone in some studies.
Highly malignant tumor with a poor prognosis. Tumor stage is very important. For example, in one study of yolk sac tumors of the mediastinum comprising 21 cases with clinical follow-up, 17 patients died of their tumors. Of these, 10 patients were Stage III (with metastases to the lung). Four patients appeared to follow a less aggressive behavior, with survival of up to 13 years. Two of these were Stage II and received aggressive chemotherapy (Moran).
1 Fletcher CDM, ed. Diagnostic Histopathology of Tumors. 3rd Ed. Philadelphia, PA: Elsevier; 2007: 1340-2.
Moran CA, Suster S, Koss MN. Primary germ cell tumors of the mediastinum: III. Yolk sac tumor, embryonal carcinoma, choriocarcinoma, and combined nonteratomatous germ cell tumors of the mediastinum--a clinicopathologic and immunohistochemical study of 64 cases. Cancer. 1997 Aug 15;80(4):699-707.