Metastases to the thyroid gland: ultrasonographic findings and diagnostic value of fine-needle aspiration cytology

Abstract

IntroductionIn the present study, we aimed to analyze ultrasonographic findings of metastases to the thyroid and explore the role of fine-needle aspiration cytology (FNAC) in the diagnosis of metastases to the thyroid.MethodsTwelve cases of cytologically or/and pathologically confirmed metastatic tumors of the thyroid gland were reviewed. All the primary thyroid lesions and lymphomas were excluded. The location, maximum size, echogenicity, shape, margin, presence of calcifications, vascularity, and cervical lymph nodes were assessed on ultrasonography. In addition, the results of cytology or pathology (or both) were noted retrospectively.ResultsEight of 10 patients were diagnosed correctly with FNAC. Two cases presented with diffuse involvement in both thyroid lobes. Nine cases demonstrated a hypoechoic nodule with an irregular margin, four of which had microcalcifications. One case presented with a mixed solid and cystic mass with an oval shape. The lesions with cervical lymph nodes were found in seven cases.ConclusionMost metastatic thyroid cancer has similar ultrasound features to primary thyroid cancer. In some cases with atypical US features, ultrasound diagnosis should be combined with the medical history. FNAC might be helpful in the diagnosis.

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

“…A search in Pubmed found only 9 studies on SMTG containing at least 8 cases with the following keywords (FNA biopsy, metastatic, thyroid, and secondary). [17][18][19][20][21][22][23][24][25] In contrast, the number of cases included in our study was higher and the clinical information and IHC-related data were more comprehensive.…”

“…These adenocarcinoma cell clusters had more pronounced nuclear heterogeneity when compared with PTC. 20,29 Metastatic renal carcinomas were the most common pitfall in previous series. 18,22 Smears of metastatic breast and renal carcinomas usually show mild and moderate cellular atypia; therefore, previous studies have suggested that metastases of renal and breast adenocarcinomas were almost indistinguishable from follicular tumor and PTC on cytologic grounds.…”

“…The nodules generally appear as a focal hypoechoic nodule with irregular margins, which is consistent with our study. 20,26 Previous studies have suggested that nodules with suspicious ultrasound features and without microcalcifications may suggest SMTG in patients with a history of nonthyroidal malignancy. 26,27 However, both in Tang 20 and our study showed that microcalcified lesions could be present in some cases.…”

“…20,26 Previous studies have suggested that nodules with suspicious ultrasound features and without microcalcifications may suggest SMTG in patients with a history of nonthyroidal malignancy. 26,27 However, both in Tang 20 and our study showed that microcalcified lesions could be present in some cases. As most metastatic thyroid tumors have ultrasound features similar to primary thyroid cancer, FNA is still required to make a definitive pathological diagnosis.…”

“…However, because secondary thyroid tumors do not have specific clinical features, and some patients do not have a history of malignancy prior to undergoing thyroid FNA, imaging of the patient beyond the thyroid can be equally helpful in finding the primary lesion. A few sporadic studies have analyzed the clinical features of secondary thyroid tumors, [11][12][13][14][15] whereas only a few studies have focused on FNA pathologic features, [16][17][18][19][20] almost no studies have mentioned the role played by imaging evidence outside the thyroid. To expand on these findings, we evaluated the role of cytomorphologic features, IHC, clinical history, and imaging evidence in the diagnosis of various secondary thyroid tumors by summarizing a 5-year experience at Shaanxi Provincial People's Hospital.…”