Metastatic Clear Cell Renal Cell Carcinoma Involving the Thyroid Gland: A Clinicopathologic Study of 17 Patients

Fine-needle aspiration diagnosis of secondary malignant tumors of the thyroid gland: A single-institution experience of 17 cases

BACKGROUND

Fine-needle aspiration (FNA) is the most commonly used preoperative pathological diagnostic tool for thyroid tumors. Secondary malignant tumors of the thyroid gland account for less than 3% of all thyroid malignancies. The aim of this study was to investigate the types and cytopathological features of secondary thyroid tumors, evaluate diagnostic pitfalls in FNA.

METHODS

Cases of secondary thyroid tumors diagnosed in the Department of Pathology of Shaanxi Provincial People's Hospital were collected, and their clinical data, cytologic features, immunohistochemical results, and histopathological diagnoses were summarized.

RESULTS

The study included 17 cases (8 males and 9 females) with a mean age of 60.4 ± 9.4 years (range, 45-83 years). Six cases had a known history of primary malignancy prior to FNA aspiration diagnosis. The most common organs of origin were the lungs (5 cases, 3 adenocarcinoma, and 2 small-cell carcinoma) and esophagus (5 cases, 3 squamous-cell carcinoma, 1 adenocarcinoma, and 1 small-cell carcinoma). The next most common was squamous-cell carcinoma of the larynx (3 cases), and gastric tumor (2 cases), including 1 lymphoma and 1 adenocarcinoma. Cell blocks and immunohistochemistry were performed in 12 of these cases. Comparison of the impact of positive history and IHC availability on the accuracy of pathologic diagnosis showed that both were statistically significant.

CONCLUSION

FNA is an effective means of diagnosing secondary malignancies of the thyroid, in which knowledge of the patient's history of malignancy is essential, and the use of cell blocks and immunohistochemistry helps to clarify the pathological diagnosis.

Papillary thyroid carcinoma with clear cell renal cell carcinoma metastasized to the thyroid gland: A case report

Metastasis of clear cell renal cell carcinoma (ccRCC) to the thyroid gland is rare, and simultaneous occurrence of ccRCC and papillary thyroid carcinoma (PTC) is even rarer. Due to the occult nature of the disease, the clinical diagnosis is difficult. In the case of multiple tumors, the possibility of thyroid metastasis should not be ignored during the clinical diagnosis and treatment of PTC. The present study reported a case with initial diagnosis of PTC and accidental discovery of thyroid metastasis of ccRCC. This case study aims to improve the understanding of occult thyroid metastasis, providing a reference for its clinical diagnosis and treatment. Accordingly, misdiagnosis and missed diagnosis of this disease may be reduced and the survival rate and the life quality of patients can be improved.

Tumor-to-tumor spread: a case report and literature review of renal cell carcinoma metastasis into thyroid cancer

Tumor-to-tumor metastasis is a rare, yet important entity. Patients with a history of renal cell carcinoma (RCC) may have tumor deposits to the thyroid gland preceding or following their initial cancer diagnosis for many years. The diagnosis can be challenging, and clinicians must remain suspicious of a newly found thyroid nodule in a patient with a history of RCC. In this review, we report a case of a patient with RCC who was incidentally found to have a thyroid nodule on surveillance imaging found to be consistent with tumor-to-tumor metastasis from RCC into papillary thyroid carcinoma. It is imperative to consider this diagnosis as the thyroid is the most common site of spread, and treatment with partial or total thyroidectomy has led to improved survival.

Clinical, cytological, and pathological characteristics of metastatic renal cell carcinoma to the thyroid: A study of 14 cases at a Japanese single institution

A preoperative diagnosis of metastatic renal cell carcinoma to the thyroid (MRCCT) is important for determining clinical management but is challenging even in cases with a clinical history of renal cell carcinoma (RCC). This study aimed to elucidate the clinical, cytological, and pathological characteristics of MRCCT. Fourteen MRCCT cases extracted from 18 320 malignant thyroid tumors were included in this study. Twelve MRCCT (85.7%) occurred as solitary lesions and the most frequently suspected lesions on ultrasonography were follicular tumors. On cytology, 46.2% of cases were reported as RCC or suspected RCC; a medical history of RCC and immunocytochemistry were helpful in interpretation. RCC metastasized to a follicular adenoma in 50.0% of the solitary lesions. MRCCTs with a long interval from the initial presentation, solitary lesion, and Ki-67 labeling index <10% showed significantly longer disease-free survival. MRCCT is characterized by a long interval from the initial presentation of RCC, appearance as a solitary nodule, ultrasonographic similarity to follicular tumors, sharing cytological findings with primary thyroid tumors, and high frequency of metastasis within follicular adenoma. A long interval from the initial presentation, occurrence as a solitary lesion, and low Ki-67 labeling index may be favorable prognostic factors.