Original ArticlesMalignant Mixed Germ Cell Tumors of the Ovary An Analysis of 100 Cases Emphasizing the Frequency and Interrelationships of Their Tumor TypesSafdar, Nida S. MD; Stall, Jennifer N. MD; Young, Robert H. MDAuthor Information James Homer Wright Pathology Laboratories, Massachusetts General Hospital, Harvard Medical School, Boston, MA Present address: Jennifer N. Stall, Hospital Pathology Associates, Virginia Piper Cancer Institute, Minneapolis, MN. Conflicts of Interest and Source of Funding: The authors have disclosed that they have no significant relationships with, or financial interest in, any commercial companies pertaining to this article. Correspondence: Nida S. Safdar, MD, James Homer Wright Pathology Laboratories, Massachusetts General Hospital, Harvard Medical School, 55 Fruit Street, Warren Building, 2nd Floor, Boston, MA 02114 (e-mail: [email protected]). The American Journal of Surgical Pathology: June 2021 - Volume 45 - Issue 6 - p 727-741 doi: 10.1097/PAS.0000000000001625 Buy Metrics Abstract One hundred malignant mixed germ cell tumors of the ovary that occurred in patients 3 to 55 years (mean: 20 y) of age are described. The clinical presentation was usually that of any highly malignant tumor of the ovary (abdominal pain and distension), but rarely (3 cases) endocrine manifestations were present. The tumors were usually unilateral (96%), ranged from 4 to 38 cm (mean: 16 cm), and were uniformly solid or, more often, solid and cystic; occasionally the typical appearance of dysgerminoma could be appreciated. The most common tumor type was yolk sac tumor (91%), followed by dysgerminoma (61%), immature teratoma (58%), embryonal carcinoma (38%), and choriocarcinoma (11%). A variety of admixtures were encountered; dysgerminoma and yolk sac tumor was the most common combination (25% of the tumors) with the 2 components often being sharply demarcated. Immature teratoma and yolk sac tumor was the next most common pairing (20%) followed by yolk sac tumor and embryonal carcinoma, with or without immature teratoma (16%). Tumors with a choriocarcinoma component had the most varied combinations of tumor types. Embryoid bodies were seen in 21% of the tumors, most often as fragmented forms arranged in a nodular manner with yolk sac tumor and/or embryonal carcinoma; uncommonly they occurred singly or in clusters. Numerous confluent well-formed embryoid bodies (polyembryoma) were prominent in 2 tumors. Three tumors had a focal diffuse embryoma pattern. The specific tumor types showed the known diverse spectrum of microscopic appearances, but the frequent haphazard arrangement of 2 or more subtypes often resulted in complex morphology. Overgrowth of another neoplastic component, most often primitive neuroectodermal tumor, occurred in 10% of the tumors further complicating the histologic picture. This is the largest series of ovarian malignant mixed germ cell tumors reported and details their characteristics including associations of their subtypes and the frequent apparent role of embryoid bodies in giving rise to yolk sac tumor and embryonal carcinoma components. Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.