Badawi Fatima, Meliti Abdelrazak
Department of Pathology and Laboratory Medicine, King Abdulaziz Medical City, Jeddah, SAU.
Department of Pathology and Laboratory Medicine, King Faisal Specialist Hospital and Research Centre, Jeddah, SAU.
Cureus. 2022 Apr 1;14(4):e23742. doi: 10.7759/cureus.23742. eCollection 2022 Apr.
Renal cell carcinoma (RCC) is the most common renal malignancy. It has a variable clinical course with metastasis to unusual sites occurring months to years after the initial diagnosis. However, metastasis can also be the first presentation of RCC. Although relatively uncommon, the thyroid gland is the most common location for RCC metastasis in the head and neck region. Tumor-to-tumor metastasis is an exceedingly rare occurrence. Only 10 cases were reported of RCC metastasis to primary thyroid neoplasms. We present a case of clear cell RCC metastasizing to a follicular of variant papillary thyroid carcinoma (FVPTC) 14 years after the initial diagnosis of RCC. A review of similar reported cases revealed that the most common primary thyroid recipient of tumor-to-tumor metastasis of RCC was FVPTC. The rich lymphovascular network in FVPTC compared to other thyroid tumors, which may promote the deposition of metastatic tumor cells, might explain this predilection. Careful review of the clinical and radiological findings and checking for any history of malignancy when examining thyroid nodules is important for guiding further studies. Performing a targeted panel of immunohistochemical stains for any suspicious areas is also essential for the diagnosis of such unusual cases.
肾细胞癌（RCC）是最常见的肾脏恶性肿瘤。其临床病程多变，在初始诊断数月至数年后可转移至不常见部位。然而，转移也可能是RCC的首发表现。甲状腺虽相对不常见，但却是头颈部RCC转移最常见的部位。肿瘤-to-肿瘤转移极为罕见。仅有10例RCC转移至原发性甲状腺肿瘤的病例报道。我们报告1例透明细胞RCC在初次诊断RCC 14年后转移至滤泡性变异型乳头状甲状腺癌（FVPTC）的病例。对类似报道病例的回顾显示，RCC肿瘤-to-肿瘤转移最常见的原发性甲状腺接受者是FVPTC。与其他甲状腺肿瘤相比，FVPTC中丰富的淋巴血管网络可能促进转移瘤细胞的沉积，这或许可以解释这种偏好。仔细回顾临床和影像学表现，并在检查甲状腺结节时排查任何恶性肿瘤病史，对于指导进一步研究很重要。对任何可疑区域进行靶向免疫组化染色检测对于诊断此类不寻常病例也至关重要。
