FOLDER 4.1 Clinical Correlation: Ovarian Teratomas (Cont.) mature basic tissues. Although the tissues fail to form functional structures, frequently organlike structures may be seen (i.e., teeth, hair, epidermis, bowel segments, and so forth). Teratomas may also develop in the testis, but they are rare. Moreover, ovarian teratomas are usually benign, whereas teratomas in the testis are composed of less-differentiated tissues that usually lead to malignancy. An example of a solid-mass ovarian teratoma containing fully differentiated tissue is shown in the center micrograph of Figure F4.1.1. The low power reveals the lack of organized structures but does not allow identification of the specific tissues present. However, with higher magnification, as shown in the insets (a–f) mature differentiated tissues are evident. This tumor represents a mature teratoma of the ovary often called a demoid cyst. This benign tumor has a normal female kariotype 46XX; based on genetic studies, these tissues are thought to arise through parthenogenic oocyte development. Mature teratomas are common ovarian tumors in childhood and in early reproductive age.
The example given in Figure F4.1.1 shows that one can readily identify tissue characteristics, even in an unorganized structure. Again, the important point is the ability to recognize aggregates of cells and to determine the special characteristics that they exhibit.
FIGURE F4.1.1  Ovarian teratoma. In the center is an H&E–stained section of an ovarian teratoma seen at low magnification. This mass is composed of various basic tissues that are well differentiated and easy to identify at higher magnification. The abnormal feature is the lack of organization of the tissues to form functional organs. The tissues within the boxed areas are seen at higher magnification in micrographs a–f. The higher magnification allows identification of some of the basic tissues that are present within this tumor. 10.
a.
Simple columnar epithelium lining a cavity of a small cyst. 170. Inset. Higher magnification of the epithelium and the underlying connective tissue. 320. b. Dense regular connective tissue forming a tendon like structure. 170.
c.
Area showing hyaline cartilage (C) and developing bone spicules (B). 170.
d.
Brain tissue with glial cells. 170.
e.
Cardiac muscle fibers. 220. Inset. Higher magnification showing intercalated disks (arrows). 320. f. Skeletal muscle fibers cut in cross section. 220.