Abstract：
An 82-year-old woman was referred to our hospital because of a suspicious thyroid nodule. She was diagnosed with papillary microcarcinoma with a maximum diameter of 9 mm based on ultrasonography and fine-needle aspiration (FNA) cytology. She preferred observation without surgery. Her papillary carcinoma grew gradually and reached a maximum diameter of 19 mm after 23 months. At that time, ultrasonography showed an apparent change in the shape of the nodule as well as in its diameter. At the initial ultrasound examination, papillary microcarcinoma was demonstrated as a hypoechoic solid nodule with an irregular shape. No punctuate microcalcifications were shown. After 23 months, the preexisting nodule had expanded toward the common carotid artery. The expanded portion was round and well demarcated. FNA revealed that the expanded portion consisted of anaplastic thyroid carcinoma. She underwent hemithyroidectomy and lymph node dissection of the central compartment. She remained in good health for 18 months after surgery. Anaplastic thyroid carcinoma is generally found as an aggressive large tumor, and the ultrasound appearance of small anaplastic thyroid carcinoma is poorly understood at present. We successfully detected anaplastic transformation in the early period by ultrasonography and FNA. When observation is indicated for small papillary thyroid carcinoma, the change in the shape of the nodule as well as in its diameter should be carefully monitored by ultrasonography. FNA should be performed at a proper site on the nodule to avoid overlooking anaplastic transformation, as resection following the early detection of anaplastic transformation might bring a favorable prognosis.
摘要：
一名82岁的妇女因可疑甲状腺结节被转诊到我们医院。根据超声检查和细针穿刺（FNA）细胞学检查，她被诊断为乳头状微小癌，最大直径为9mm。她更喜欢不做手术的观察。她的乳头状癌逐渐增长，并在23个月后达到19毫米的最大直径。当时,超声检查显示结节的形状和直径有明显变化。在最初的超声检查中，乳头状微小癌被证明是具有不规则形状的低回声实性结节。未显示点状微钙化。23个月后,先前存在的结节向颈总动脉扩张。扩展部分是圆形的，并且边界很好。FNA显示，扩展部分由间变性甲状腺癌组成。她接受了半甲状腺切除术和中央室淋巴结清扫术。手术后18个月，她的健康状况良好。间变性甲状腺癌通常是一种侵袭性的大型肿瘤，目前对甲状腺微小间变性癌的超声表现知之甚少。我们通过超声和FNA成功地检测了早期的间变性。当观察到小乳头状甲状腺癌时，应通过超声检查仔细监测结节形状和直径的变化。FNA应在结节的适当部位进行，以避免忽略间变性，因为早期发现间变性转化后的切除可能会带来良好的预后。
