Metastases to the thyroid presenting as a metabolically inactive incidental thyroid nodule with stable size in 15 months.

Subhashini Yaturu,Raina A Patel

doi:10.1155/2014/643986

Abstract

Though the thyroid gland has a rich vascular supply, incidence of metastatic disease from distant organs is rare. Here we present an unusual case of metastases to the thyroid with several interesting features. A 63-year-old male with history of adenocarcinoma of the right lobe lung (5 years prior to presentation), treated with surgery and chemotherapy, followed by new adenosquamous lung cancer in the left lobe of the lung (one year prior to presentation), treated surgically followed by adjuvant chemotherapy, was referred to Endocrinology section for evaluation of an incidental thyroid nodule on CT chest. Ultrasound (US) of the thyroid revealed a complex, predominantly hypoechoic lesion measuring 1.8 cm within the lower pole of the right thyroid lobe and a subcentimeter lesion in the left lobe of the thyroid. Review of prior CT chests showed that the lesion in the right lobe was stable for 15 months, with no evidence of a hypermetabolic lesion on PET scan. The subcentimeter lesion was not seen on prior CT scans. US guided fine needle aspiration (FNA) and pathology of the lobectomy of the thyroid confirmed adenosquamous carcinoma. Interesting features in this case are that the thyroid metastases occurred without any evidence of synchronous lesions elsewhere, the size was stable over 15 months, and the lesions were metabolically inactive.

Highlights

Relevant metastatic neoplasms to the thyroid gland are rare
Since the lesion was present at the time of the second malignancy (it is seen in the March 2011 CT, Figure 1(a)), the chemotherapy for the adenosquamous carcinoma may have decreased the rapidity of growth of the metastatic lesion
The second interesting feature is that there is no uptake on PET with F-18 deoxyglucose (FDG) in the thyroid nodule, indicating that the metastatic lesion was metabolically inactive

Summary

Background

Relevant metastatic neoplasms to the thyroid gland are rare. Secondary thyroid tumors may be accompanied by synchronous metastatic lesions to other organs, for example, to the lungs. In a 43-case clinical review, the location of the primary tumor in secondary tumors to thyroid is reported to be as follows: kidney as the most common primary tumor site (33%), followed by lung (16%), breast (16%), esophagus (9%), and uterus (7%) [1]. A recent literature review reports that the most common nonthyroidal malignancies that metastasize to the thyroid include in the order of frequency are renal cell carcinoma (48%), colorectal cancer (10.4%), lung cancer (8.3%), breast cancer (7.8%), and sarcoma (4.0%) [2]. We present an interesting case with secondary tumor to thyroid without synchronous lesions elsewhere and with stable size for 15 months

Clinical Case

Discussion

Findings

Conclusion