International Journal of Clinical Case Reports 2016, Vol.6, No.24, 1-7
6
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.
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