Struma ovarii is composed entirely of –
**Core Concept**
Struma ovarii is a rare type of ovarian teratoma (benign tumor) that is predominantly composed of thyroid tissue. It is a variant of mature teratoma, which contains cells from all three germ layers: ectoderm, endoderm, and mesoderm. In struma ovarii, the endodermal component is predominantly thyroid tissue.
**Why the Correct Answer is Right**
Struma ovarii is characterized by the presence of thyroid follicles, which contain colloid and thyroid epithelial cells. The thyroid tissue in struma ovarii can produce thyroid hormones, leading to hyperthyroidism in some cases. The presence of thyroid tissue in the ovary is thought to arise from the migration of thyroid anlage cells during embryonic development.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not mentioned in the context of struma ovarii composition. While ovarian teratomas can contain a variety of tissues, struma ovarii is specifically characterized by its thyroid tissue composition.
* **Option B:** This option is not a characteristic of struma ovarii. While ovarian teratomas can contain cartilage, bone, and other tissues, struma ovarii is primarily composed of thyroid tissue.
* **Option C:** This option is not accurate. While ovarian teratomas can contain a variety of tissues, struma ovarii is specifically characterized by its thyroid tissue composition, not adrenal tissue.
**Clinical Pearl / High-Yield Fact**
Struma ovarii can mimic other ovarian tumors, such as dermoid cysts or mucinous cystadenomas, on imaging studies. A key feature that may suggest struma ovarii is the presence of calcifications or a "ground-glass" appearance on ultrasound or CT scans.
**Correct Answer:** Not Provided - The original question provided had no options A, B, C, D. However, based on the context, the correct answer would typically be: **D. Thyroid tissue**