Renal Cell Carcinoma Metastatic to Thyroid Gland, Presenting Like Anaplastic Carcinoma of Thyroid

Abstract

Background. Renal cell carcinoma (RCC) has unpredictable and diverse behavior. The classic triad of hematuria, loin pain, and abdominal mass is uncommon. At time of diagnosis, 25%–30% of patients are found to have metastases. Bones, lungs, liver, and brain are the frequent sites of metastases. RCC with metastasis to the head and neck region and thyroid gland is the rarest manifestation and anaplastic carcinoma behaving metastatic thyroid mass is an extremely rare presentation of RCC. Case Presentation. A 56-year-old Saudi man with past history of right radical nephrectomy 5 years back presented with 3 months history of rapid increasing neck mass with dysphagia, presenting like anaplastic thyroid carcinoma. Tru-cut biopsy turned out to be metastatic renal cell carcinoma. Patient was treated with radiation therapy 30 Gy in 10 fractions to mass. Patient died 4 months after the discovery of anaplastic thyroid looking metastasis. Conclusion. Rapidly progressing thyroid metastases secondary to RCC are rare and found often unresectable which are not amenable to surgery. Palliative radiotherapy can be considered for such patients.

Metastatic Renal Cell Carcinoma of the Thyroid

“…RCC is the most common malignant epithelial tumor of the kidney, accounting for 85-90% of all solid renal tumors in adults [2]. In almost half of the patients with RCC, metastasis was noted at the time of presentation [3]. There are three major types of RCC.…”

“…The spread of non-thyroid malignancies in the thyroid has been reported in 1.4-3% of patients with thyroid malignancies undergoing thyroid surgery [7]. The thyroid gland is among the most vascularized organs in the body and hence is vulnerable to metastatic disease [3]. The most common sources of metastases to the thyroid include kidney, skin, breast, and lung, and head and neck, but more than 50% of the time the source is RCC in clinically recognized metastasis to the thyroid [8,9].…”

Metastasis from renal cell carcinoma to thyroid presenting as rapidly growing neck mass

“…It has been proposed that because of the high iodine and oxygen concentration and the abundant high-velocity bloodstream in the thyroid gland, which prevent tumor cells from being fixed, the thyroid gland has a low frequency of clinical metastatic carcinoma, but if the above-mentioned concentration is altered because of a goiter or thyroiditis, the thyroid gland becomes more vulnerable to metastatic growth. 5 …”

Secondary or Second Primary Malignancy in the Thyroid? Metastatic Tumors Suggested Clinically: A Differential Diagnostic Task

“…In the scientific literature, many cases of metastatic tumors in the thyroid have been published as case reports describing the pitfalls of individual case diagnosis supported by a literature overview, stressing the specific context of the more frequent primary malignancies or the reporting a rare malignancy metastasizing to the thyroid [11,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31]. Meta-analyses are available for the most frequent primary malignancies [32,33].…”