1 Introduction

The kidney cancer’s thyroid metastases are very rare. The renal cancer is well known for his unpredictable evolution, it is called the tumor of the "internist". The best known of this cancer metastatic sites are the bone, the lymph nodes and the lung, while the thyroid metastases are rare. The distinction between a metastasis and thyroid malignancy by the clinical examination and the imaging is difficult, only the patient history can guide the diagnosis to be affirmed by the histological examination.

2 Case Report

We report on a 74-year-old man who was treated for high blood pressure with a family history of breast cancer in the sister. Our patient consulted for a neck mass with dysphonia and dyspnea (Figure 1).

The clinical examination showed a large nodular goiter (130/90mm), painful, fixed and suspect with a collateral circulation. The cervical ultrasound revealed a left side basicervical mass richly vascularized (Figure 2). The hormonal balance was normal. The thyroid scan showed cold nodules. The pathological results of the mass biopsy (immunohistochemistry) confirmed the thyroid metastasis of cytokeratin clear cells carcinoma (AE1 / A3 + vimentin + CD10 - PS 100 - Chromogranin A- Synaptophysin-).

The cervical-thoracic-abdominal CT scan showed a right lateral well encapsulated renal tumor (40/35mm) with a development outside the kidney and multiple calcifications (Figure 3), and a left laterocervical process (62/54/90mm), and a mediastinal process (55/53/82mm) with pulmonary nodules with tracheal compression and upper thoracic parietal process 130/88/89mm, sternal bone loss and multiple inferior right pulmonary nodules (Figure 4).

The bone scintigraphy showed two foci uptake (sternal manubrium and the 11th posterior left rib).

Our patient was classified intermediate group (Heng classification, Table 1).

On September 2014, the patient was operated; an enlarged right radical nephrectomy was performed. The pathology study revealed a tubulo-papillary carcinoma of the right kidney, grade II of FUHRMAN (Gravitz tumor, Figure 5).

On February 2016, the patient underwent a targeted therapy (sunitinib: 50 mg for 4 weeks and followed by two weeks without the treatment, eight cures).

The radiological evaluation after treatment found a regression of cervical, mediastinal and parietal lesions (with an increase in necrosis areas) and a partial response of the pulmonary nodules with a good tolerance (Figure 6).

3 Discussion

The thyroid metastases are rare, a recent study showed that 1.9 to 22.4% of patients with generalized cancer, had thyroid metastases after an evaluation at the autopsy (Mohammadi et al., 2014). The tumors that metastasize to the thyroid gland are the melanoma (39%), the breast cancer (31%) and the lung cancer (25%), while the renal cancer rarely metastasis on the thyroid gland due to the high concentration of the iodine and the oxygen in the thyroid (Bakhos et al., 2006). The increase of the villus of the bloodstream of the thyroid gland prevents the tumor cells attachment. But, if the concentration drops because of a goiter or a thyroiditis, the thyroid becomes more vulnerable to metastatic growth, while the thyroid hormone balance and metering thyrocalcitonin are normal and the cervical ultrasound shows a hyperechoic swelling and the thyroid scan a cold nodule. The cervical CT scans with and without injection can find calcifications in the thyroid parenchyma, an isolated nodule or a multi nodular thyroid swelling, it assesses the impact on the surrounding organs (Sindoni et al., 2010; Medas et al., 2013). In his study (11 cases), Takashima found that the thyroid nodules were solitary in five cases and multiple in six cases, and over 50% were less than 2 cm (Takashima et al., 2000). The fine needle aspiration (FNA) using ultrasound of a thyroid nodule in a patient with a history of cancer should be systematic and directs the diagnosis, but only the histology and the immunohistochemistry allows the definitive diagnosis (Chin et al,. 2011).

The histology in case of metastasis from renal cancer notes an encapsulated lesion cells with clear cytoplasm, abundant and round nuclei with hyperdense chromatin. The immunostaining for thyroglobulin and calcitonin are negative.

The treatment of the thyroid metastasis is discussed according to the histological type, the location and the metastatic evolution of the primitive cancer. The thyroid surgery is proposed if the thyroid metastasis is isolated or if the other metastatic sites are operable.

The surgical resection of these metastases appears to increase median survival, especially in cases of metachronous metastases (ten years) against synchronous metastases (eight months). In the absence of cervical lymph node metastasis, there is no need to the lymphadenectomy. The contra-indicate of surgery are the tracheal and the esophageal invasion (Sindoni et al., 2010; Medas et al., 2013). Two good prognostic factors for the thyroid metastases with primary renal cancer are isolated thyroid metastasis whose the resection was complete and a long interval between the nephrectomy and the appearance of the metastasis (up to 20 years). In case of multiple metastases, the survival rate at five years is 5%.

4 Conclusion

The secondary thyroid metastatic renal cancer is rare. It is necessary to suggest the diagnosis of the thyroid metastasis before the onset of the thyroid swelling or the recurrent laryngeal paralysis in a patient with previous cancers. The FNA and the thyroid histology must be systematic.

The treatment of the thyroid metastasis is decided according to the renal cancer metastasis, and the thyroidectomy is recommended in case of isolated metastatic thyroid location.

Author’s contributions

By signing this letter each of us acknowledges that he participated sufficiently in the work to take public responsibility for it.

References

Mohammadi A., Toomatari SB., and Ghasemi-Rad M., 2014, Metastasis from renal cell carcinoma to thyroid presenting as rapidly growing neck mass, Int J Surg Case Rep, 5(12):1110-2. doi: 10.1016/j.ijscr.2014.09.010.

http://dx.doi.org/10.1016/j.ijscr.2014.09.010

Bakhos D., Lescanne E., Beutter P., et al., 2007, Metastasis of renal carcinoma to the thyroid gland, Ann Otolaryngol Chir Cervicofac, 124(6):301-4.

http://dx.doi.org/10.1016/j.aorl.2006.11.003

`PMid:17673161

Sindoni A., Rizzo M., Tuccari G, et al., 2010, Thyroid metastases from renal cell carcinoma: review of the literature, ScientificWorldJournal, 10:590-602. doi: 10.1100/tsw.2010.55.

http://dx.doi.org/10.1100/tsw.2010.55

Medas F., Calò PG., Lai ML., et al., 2013, Renal cell carcinoma metastasis to thyroid tumor: a case report and review of the literature, J Med Case Rep, 10, 7:265. doi: 10.1186/1752-1947-7-265.

http://dx.doi.org/10.1186/1752-1947-7-265

Takashima S., Takayama F., Wang J C., et al., 2000, Radiologic assessment of metastases to the thyroid gland, j Comput Assist Tomogr, 24 : 539-545.

Chin CJ., Franklin JH., Moussa M., et al., 2011, Metastasis from renal cell carcinoma to the thyroid 12 years after nephrectomy, CMAJ. 6, 183(12):1398-9. doi: 10.1503/cmaj.092152.

http://dx.doi.org/10.1503/cmaj.092152