Adenomyosis & Struma Ovarii

This Daily Doodle illustrates two different conditions: adenomyosis and struma ovarii. To note, there is no link between the two – I just wanted to include both cases on one doodle.

Adenomyosis is a condition when the endometrium (inner lining of the uterus) infiltrates the myometrium, the muscular layer. This causes a global enlargement of the uterus. Symptoms include painful menstruation (dysmenorrhea) and increased bleeding (menorrhagia). More myometrium = more bleeding.

During my OBGYN rotation, I spent a few days with the pathologist to learn more about gynecological pathology. While I was looking at slides of ovarian pathology under the microscope, the pathologist gave me a slide and asked what I saw. I took a look and scratched my head, “It looks like thyroid tissue with colloid in the center…” I was right! It was thyroid tissue, but it was growing in the ovary. This rare ovarian tumor is called struma ovarii.

Struma ovarii, as seen on the right hand side of the doodle, is a monodermal teratoma which contains thyroid tissue. Its name, struma ovarii, literally means “Goitre of the Ovary.” Depending on the histologic findings, the tumor may be classified as benign or malignant. It occurs most commonly in women between the ages of 40 and 60 years and typically presents with lower abdominal pain and/or a pelvic mass and less frequently with ascites. Even though the tumor contains mature thyroid tissue, “clinical and biochemical features of hyperthyroidism are uncommon in women with struma ovarii, occurring in less than 5 to 8 percent of cases” (2).

The treatment of benign struma ovarii is surgical resection of the ovarian tumor (unilateral oophorectomy). If malignant, patients may require more extensive resection including hysterectomy and additional therapy, such as radioactive iodine.


  1. E. Stewart. “Uterine Adenomyosis” Uptodate.
  2. D. Ross. “Struma Ovarii”. Uptodate.

“Adenomyosis and Struma Ovarii” Daily Doodle by Michiko Maruyama

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