Papillary thyroid carcinoma is associated with a good prognosis and with a low metastatic power. A distant metastasis from papillary thyroid carcinoma is a rare event, above all when the recurrence occurs in less common sites. For this reason, rare metastasis is often not considered during the clinical setting.
When an ovarian mass is found to contain cells with features of thyroid carcinoma, a differential diagnoses should have to be considered between thyroid cancer arising from a struma ovarii and ovarian metastasis originating from a primary thyroid carcinoma, since the prognosis and clinical management are different. Thyroid carcinoma originating from a struma ovarii, presenting a papillary histotype in 70% of all cases, is reported to occur much more commonly than an ovarian metastasis from the thyroid. As a matter of fact, struma ovarii are the 5% of ovarian teratomas, 5-10% results in malignant teratomas and metastatic diseases doesn't reach the 23% of cases. However, when no teratomatous elements and no normal thyroid epithelial tissue are detected in the ovarian lesion, the diagnosis of metastasis with a thyroid origin is suggestive [
7]. In our patient, the ovarian parenchyma was completely occupied by thyroid-type neoplasm, there was no evidence of benign struma ovary or others teratomatous component and cells were positive to TTF-1 and Thyroglobulin antibodies.
A review of literature from 1929 to 2013 can confirm the rarity of the ovarian metastasis from thyroid carcinoma. As it is shown in Table
1, only four case reports of ovarian metastasis from thyroid are described in a comprehensive manner [
8]-[
11]. The table shows that most of patients affected by thyroid carcinoma were between the fourth and fifth decades of life at the moment of the first diagnosis and underwent I
131 therapy after primary surgery. Moreover, ovarian metastasis seems to appear more commonly unilaterally. It can be inferred from the description of these cases that well differentiated thyroid carcinomas can give metastasis many years after the primary tumor. As a matter of fact, in Brogioni S et al. [
10] case report, the ovarian metastasis occurred almost 5 years after the first pulmonary metastasis and 7 years after the first diagnosis. Also in Pirvu A et al. [
11] report, the pulmonary metastasis occurred shortly after the thyroidectomy, while ovarian metastasis 11 years after the first diagnosis of thyroid carcinoma. Furthermore, in the well differentiated thyroid cancer group, papillary histotype seems to give ovarian metastasis more frequently than follicular. In our case ovaries had been the first metastatic site, while in three of the mentioned reports [
8],[
10],[
11], the ovarian metastasis was associated with a metastatic spread, probably pointing to a biologically more aggressive disease and to a worse prognosis associated to the ovarian involvement. Further 10 cases [
12]-[
18] of ovarian spread from thyroid carcinoma are mentioned in literature but, unfortunately, no more details were provided. Besic et al. [
12] in his autoptic series reported one case of ovarian metastasis from anaplastic thyroid carcinoma, while Silvesberg et al. [
13], always in autoptic series, reported two cases of ovarian metastasis from anaplastic thyroid carcinoma and one from medullary thyroid carcinoma. Others two cases of ovarian metastasis from medullary thyroid carcinoma are only mentioned by Ibanez et al. [
14] and Gordon et al. [
15]. In another article [
17] the ovarian involvement was bilateral. However, in literature there are not enough studies to draw conclusions about prognosis and best clinical management of ovarian metastasis from thyroid cancer.
131I scan and serum thyroglobulin are widely employed during the follow up of thyroid cancer and in the assessment of the best therapy to use after surgery, while immunohistochemical stain for thyroglobulin and TTF-1 is often essential in pathologic diagnosis as it has been in our experience. Moreover, Keratin-19 (CK-19) e HBME-1 were positive while Galectin-3 (GAL-3) was negative. This was due to because GAL-3 is a useful marker for diagnosis of low grade thyroid carcinomas [
19] while in our case the carcinoma was an high grade.
Table 1
Literature review of ovarian metastasis from thyroid carcinoma
| 1994 | 1 | 17 | Partial thyroidectomy | Follicular | - | 144 | Brain, ovaries | Right cystectomy | - | DOD, 150 |
| 2001 | 1 | 34 | Total thyroidectomy with lymphadenectomy | Papillary | Yes | 132 | Ovaries | Left oophorectomy | Yes | NED, 140 |
| 2007 | 1 | 38 | Total thyroidectomy, with lymphadenectomy | Papillary | Yes | 24 | Thymus, lungs, ovaries, brain | Bilateral oophorectomy | Yes | DOD, 92 |
| 2013 | 1 | 26 | Total thyroidectomy with lymphadenectomy | Papillary | Yes | - | Lungs, ovaries | Left ovariectomy | Yes | AWD, 158 |
Our experience | 2014 | 1 | 42 | Total tyroidectomy | Papillary | Yes | 108 | Ovaries | Laparoscopic bilateral oophorectomy | No | AWD, 111 |
In conclusion, the ovarian involvement by a primary thyroid cancer is a rare event, but it should be considered, since it seems to be a negative prognostic factor worsening the oncological outcome. The histopathologic evaluation, including immunohistochemical stain and the investigation of patient's history are crucial steps in the diagnosis and clinical management of ovarian metastasis from thyroid cancer.