Hyalinizing trabecular tumor (HTT) of the thyroid is a mostly benign disease. Its cytological and pathological diagnosis is often difficult, because HTT cells and papillary thyroid carcinoma (PTC) cells share similar features (e.g., intranuclear cytoplasmic inclusions and nuclear grooves). At our institution, 38 patients were diagnosed as or highly suspected of having HTT without the possibility of PTC, based on cytology: 19 of these patients underwent immediate surgery (surgery group) and the remaining 19 underwent active surveillance without surgery (AS group). The surgery-group patients’ tumor sizes were significantly larger (p < 0.0001) than those in the AS group. During AS (median 38 months), only one patient (5%) showed tumor enlargement by ≥3 mm; the AS was continued. Of the 34 patients pathologically diagnosed with HTT, 22 (65%) were cytologically diagnosed or highly suspected as having HTT without the possibility of PTC. Of the nine patients who were suspected to have HTT but PTC was possible and surgery was performed, two (22%) and seven (78%) were pathologically diagnosed as having PTC and HTT, respectively. Five patients were cytologically diagnosed with PTC, but pathologically diagnosed as having HTT. No patients showed HTT recurrence during postoperative follow-up (median 60 months). These findings suggest that (1) active surveillance can be a valid strategy for managing tumors that are cytologically diagnosed as HTT with no possibility of PTC; (2) surgery is recommended for tumors suspected of being HTT but may be PTC, and (3) the prognosis of HTT in both the AS and surgery groups was excellent.

甲状腺透明样小梁瘤 (HTT) 是一种多为良性的疾病。其细胞学和病理学诊断通常很困难，因为 HTT 细胞和甲状腺乳头状癌 (PTC) 细胞具有相似的特征（例如，核内细胞质包涵体和核沟）。在我们的机构，根据细胞学检查，38 名患者被诊断为或高度怀疑患有 HTT 而没有 PTC 的可能性：其中 19 名患者接受了立即手术（手术组），其余 19 名接受了主动监测而不进行手术（AS 组）。手术组患者肿瘤体积明显增大（p< 0.0001) 高于 AS 组。在 AS 期间（中位 38 个月），只有 1 名患者（5%）显示肿瘤增大 ≥3 mm；AS 继续。在病理诊断为 HTT 的 34 例患者中，22 例 (65%) 经细胞学诊断或高度怀疑为 HTT 而没有 PTC 的可能性。在怀疑患有 HTT 但可能发生 PTC 并进行了手术的 9 名患者中，分别有 2 名（22%）和 7 名（78%）病理诊断为患有 PTC 和 HTT。5 名患者经细胞学诊断为 PTC，但经病理学诊断为 HTT。术后随访期间（中位 60 个月）没有患者出现 HTT 复发。这些研究结果表明（1）主动监测可以成为管理细胞学诊断为 HTT 而没有 PTC 可能性的肿瘤的有效策略；