Melis Céline, Ballaux Florence, Bourgain Claire
Department of Pathology, University Hospitals of Leuven, Leuven,
Department of Pathology, Imelda Hospital, Bonheiden, Belgium.
Acta Cytol. 2018;62(5-6):443-449. doi: 10.1159/000490367. Epub 2018 Jul 13.
The most frequent metastases to the thyroid originate in the kidney, lung or breast. Colorectal adenocarcinoma represents less than 4% of metastases to the thyroid gland. Solitary metastases of colorectal cancer with no other manifestation of disseminated cancer disease are exceedingly rare. Within the Bethesda Classification for Reporting -Thyroid Cytopathology, metastases are included in Diagnostic Categories "Suspicious for Malignancy" and "Malignant."
We present 2 cases of colorectal adenocarcinoma metastatic to the thyroid gland, diagnosed by fine-needle aspiration (FNA). One metastasis occurred in normal thyroid parenchyma; the other was a tumour-to-tumour metastasis into a follicular carcinoma of the thyroid. The latter is the first published tumour-to-tumour metastasis of a colorectal carcinoma in the thyroid from which both components were diagnosed by FNA.
Diagnosing a metastasis to the thyroid is challenging. On FNA, a dual cell population should raise suspicion. Immunocytochemical and molecular analysis may be helpful. Clinical information is essential in guiding specific ancillary technique panels in scant cellular material.
甲状腺最常见的转移瘤起源于肾、肺或乳腺。结直肠癌转移至甲状腺的情况不到甲状腺转移瘤的4%。无其他播散性癌症表现的孤立性结直肠癌转移极为罕见。在《甲状腺细胞病理学报告贝塞斯达分类法》中，转移瘤被归入“可疑恶性”和“恶性”诊断类别。
我们报告2例经细针穿刺抽吸活检（FNA）诊断为结直肠癌转移至甲状腺的病例。其中1例转移至正常甲状腺实质；另1例为肿瘤至肿瘤的转移，即转移至甲状腺滤泡癌。后者是首次发表的通过FNA诊断出两种成分的结直肠癌肿瘤至肿瘤转移至甲状腺的病例。
诊断甲状腺转移瘤具有挑战性。FNA检查时，双细胞群应引起怀疑。免疫细胞化学和分子分析可能会有所帮助。临床信息对于指导细胞数量稀少时的特定辅助技术检测至关重要。
