Thyroid Research and Practice

: 2014  |  Volume : 11  |  Issue : 1  |  Page : 32--34

Incidental detection of thyroid tissue in normal ovary: Choristoma or Monodermal teratoma? Report of two cases

Bhawna Bhutoria Jain, Sarbani Chattopadyay 
 Department of Pathology, Medical College, Kolkata, West Bengal, India

Correspondence Address:
Bhawna Bhutoria Jain
862, Block P, New Alipore - 700 053, Kolkata, West Bengal


We report two cases of incidental detection of thyroid tissue in ovary. These cases were found in women who underwent hysterectomy for other causes. The sizes of ovaries were normal and there was no evidence of teratoma on multiple sections.

How to cite this article:
Jain BB, Chattopadyay S. Incidental detection of thyroid tissue in normal ovary: Choristoma or Monodermal teratoma? Report of two cases.Thyroid Res Pract 2014;11:32-34

How to cite this URL:
Jain BB, Chattopadyay S. Incidental detection of thyroid tissue in normal ovary: Choristoma or Monodermal teratoma? Report of two cases. Thyroid Res Pract [serial online] 2014 [cited 2022 Sep 28 ];11:32-34
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Thyroid tissue can be seen anywhere along the path of the descending glands, but its occurrence in the abdominal cavity is rare. [1] In ovary it is always seen as a component of mature teratoma or as struma ovarii which is a monodermal teratoma and a rare ovarian tumour characterized by the presence, entirely or predominantly, of mature thyroid tissue, presenting the same physiological and pathological changes as the thyroid gland. [2] We present two cases where thyroid tissue was detected in a normal sized ovary on routine histopathological examination.

 Case Reports

Case 1

A 40-year-female patient presented with irregular vaginal bleeding. Ultrasonography of abdomen revealed uterine fibroid approximately 6 cm for which she was operated. On gross examination the specimen consisted of uterus, cervix, and bilateral tubes and ovaries. A sub-mucous fibroid measuring 6 cm in diameter was present arising from fundus. Both the ovaries were normal in size. Routine slices from cervix, endomyometrium, fibroid; both tubes and ovaries were given for histopathological study. Microscopic examination of sections revealed chronic non-specific cervicitis, proliferative endometrium with normal myometrium, leiomyoma and no specific tubal pathology. Sections from one ovary showed distinctive thyroid tissue surrounded by normal ovarian stroma [Figure 1]. Repeat sections from the ovary to search for teratomatous elements did not reveal anything.{Figure 1}

Case 2

A 50-year-old lady underwent total hysterectomy and bilateral salpingo-oopherectomy for uncontrolled menorrhagia and adenomyosis of uterus on abdominal USG. Gross examination of the specimen showed enlarged uterus 8 × 6 × 5 cm with Nabothian cysts in cervix. The tubes showed features of ligation. Right ovary measured 3.5 × 2.5 × 1.5 cm. Cut section showed two cystic areas; one was 0.5 cm filled with brownish gelatinous material [Figure 2] and other was compressed and empty. Left ovary was normal in appearance.{Figure 2}

Microscopic examination of sections from uterus showed proliferative endometrium and adenomyosis in the myometrium. Right ovary showed a cystic luteinized follicle and a circumscribed area containing thyroid follicles, which were lined by cuboidal to flattened cells.

On further sections no other elements, which could be suggestive of teratoma were seen. Subsequently, in both the cases, thyroid was evaluated with USG, serological profile, and Iodine 131 scan. No abnormality was detected in the thyroid and, therefore, the possibility of metastatic deposit in ovary from a primary thyroid malignancy was ruled out.


The thyroid tissue starts developing during the fourth embryonic week appearing on the tongue as an epithelial growth. By the seventh embryonic week, the thyroid gland descends to the adult position, anterior to the trachea. Ectopic thyroid gland can be found along this pathway. [3]

Ectopic intra-abdominal thyroid tissues have been reported within the gallbladder, the mesentery of the small intestine, the pancreas, the porta hepatitis, the duodenum, and the space posterior to the spleen and stomach. [3] Five cases of intra-adrenal thyroid gland tissue have been reported in the literature, in women of middle age. The patients were euthyroid and ectopic gland was diagnosed on histological examination after adrenalectomy. [4] In ovary, it is observed in 5-15% of dermoid tumors, but to qualify as a struma ovarii tumor the thyroid proportion must comprise more than 50% of the overall tissue. [5] The simple presence of thyroid tissue with coexistence and predominance of other cell types does not confirm the diagnosis of struma ovarii. [2]

Choristomas are defined as heterotopic rests of normal tissue. [6] As struma ovarii is defined as teratoma in which thyroid tissue predominates, detection of thyroid tissue in the present setting fits the definition of choristoma than struma ovarii.

Struma ovarii occurs more frequently (68.8%) in the right adnexa. [7] It occurs mainly in women older than 40 years. It is usually an incidental finding or presents with pain or abdominal distention. Rare patients have ascitis and hydrothorax. Occasional patients have hormonal mediated symptoms. [8]

On pathologic examination struma ovarii is a circumscribed neoplasm average size being 5-10 cm. Cross section is usually red, green or tan with a glary, meaty appearance. Small cysts are commonly present. Microscopically, it is composed of follicles filled with colloid and lined by cells with uniform round nuclei. Degenerative changes such as fibrosis, calcification may be present. Any type of thyroid cancer can arise in struma ovarii among which papillary carcinoma is most common. [8]

Struma ovarii is benign in most instances and hence treated by cystectomy or unilateral salpingo-oopherectomy. Rare malignant tumors are best treated by hysterectomy and bilateral salpingo-oopherectomy, thyroidectomy, and by administration of radioactive iodine. [8]

In the present study, both the patients were above 40 years of age and thyroid tissue was present in right ovary. On gross examination of ovaries, overall size of the ovaries were normal in both cases; the nodules were less than 1 cm in size and the microscopic examination revealed follicles filled with eosinophilic colloid and lined by uniform cells with round nuclei. Teratoma, mature or monodermal, will cause enlargement of ovary.

The closest differential diagnosis in this case with normal sized ovary showing presence of thyroid tissue is metastasis from a well differentiated follicular thyroid carcinoma. Thyroid evaluation in both the cases by USG, thyroid hormone profile and Iodine 131 scan ruled out such a possibility.


Since the sizes of ovaries were normal and detection of thyroid tissue was incidental; considering it as Choristoma (ectopic rest of normal tissue) rather than Teratoma seems more rational.


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