Department of Pathology, Tata Memorial Hospital, Parel, Mumbai, Maharashtra, 400012, India.
Homi Bhabha National Institute, Mumbai, 400012, India.
Head Neck Pathol. 2021 Dec;15(4):1137-1146. doi: 10.1007/s12105-021-01323-7. Epub 2021 Apr 11.
Collision tumor is the occurrence of two histologically and morphologically distinct tumors within the same organ with no histological admixture. Collision tumors of the thyroid are extremely rare constituting < 1% of all thyroid tumors. Clinical profiles and pathological features of Medullary thyroid carcinoma (MTC) and Papillary thyroid carcinoma (PTC) presenting as Collision tumors of thyroid, diagnosed between 2009 and 2019, at a tertiary care cancer center were retrospectively analyzed. Collision tumors comprised 4.7% of all MTC cases diagnosed over 10 years. A total of 21 cases (11males, 11 females, M:F = 1) were retrieved with the mean age of patients being 45.33 years (range 26-77 years). More than half of PTCs involved the right lobe of the thyroid (66.6%). About half (53.4%) of MTCs affected the left lobe. Imaging done pre-operatively failed to identify the smaller second tumor in 60% of the cases with both tumours in separate lobes. Pre-operative FNAC showed only MTC in all 8 cases in which it was done. Papillary microcarcinoma (m-PTC) was seen in 85.7% cases, with one case of multifocal m-PTC. MTC (mean size 3.12 cm), on an average, was 3 times larger than the PTC (mean size 0.91 cm). The histological variants of MTC included-oncocytic (1/21, 4.7%), spindle cell (1/21, 4.7%), epithelial (3/21, 14.2%) and classical (16/21, 76.2%) and of PTC included classic PTC (12/21, 57.14%), Hurthle cell (2/21, 9.52%), tall cell (1/21, 4.76%) and follicular variant of PTC (6/21, 28.57%). The microscopic extrathyroidal extension (ETE) due to MTC and PTC component was 42.8% and 9.5% respectively. Lymph node metastasis was seen in 16 (76.2%) cases; 87.5% (14/16) of which were contributed by MTC, 12.5% (2/16) by PTC alone, and 12.5% (2/16) cases showed metastasis from both MTC and PTC. MTC had a higher stage than PTC in 85.5% of cases. Collision tumors of the thyroid are exceedingly rare, and possibly underdiagnosed due to variation in sampling techniques, especially of the grossly "normal lobe". The low incidence in our cohort is in favor of the "Chance theory" of co-occurrence. This diagnosis is important due to its therapeutic and prognostic implications.
碰撞瘤是指同一器官内发生两种组织学和形态学上明显不同的肿瘤，且无组织学混合。甲状腺碰撞瘤极为罕见，占所有甲状腺肿瘤的<1%。对 2009 年至 2019 年在一家三级癌症中心诊断的作为甲状腺碰撞瘤的甲状腺髓样癌（MTC）和甲状腺乳头状癌（PTC）的临床特征和病理特征进行回顾性分析。在 10 年期间，碰撞瘤占所有 MTC 病例的 4.7%。共检索到 21 例（男性 11 例，女性 11 例，M:F=1），患者平均年龄为 45.33 岁（26-77 岁）。超过一半的 PTC 累及甲状腺右叶（66.6%）。约一半（53.4%）的 MTC 影响左叶。术前影像学检查未能在 60%的单独位于两个不同叶的病例中识别较小的第二个肿瘤。术前细针穿刺细胞学检查（FNAC）显示 8 例中均仅为 MTC。85.7%的病例为微小乳头状癌（m-PTC），1 例为多灶性 m-PTC。MTC（平均大小 3.12cm）平均比 PTC（平均大小 0.91cm）大 3 倍。MTC 的组织学变异包括嗜酸细胞型（1/21，4.7%）、梭形细胞型（1/21，4.7%）、上皮型（3/21，14.2%）和经典型（16/21，76.2%），PTC 的组织学变异包括经典型 PTC（12/21，57.14%）、Hurthle 细胞型（2/21，9.52%）、高柱状细胞型（1/21，4.76%）和滤泡型 PTC（6/21，28.57%）。MTC 和 PTC 成分导致的甲状腺外扩展（ETE）分别为 42.8%和 9.5%。16 例（76.2%）发生淋巴结转移；其中 87.5%（14/16）由 MTC 引起，12.5%（2/16）由 PTC 单独引起，12.5%（2/16）的病例显示由 MTC 和 PTC 共同引起转移。85.5%的病例中 MTC 的分期高于 PTC。甲状腺碰撞瘤极为罕见，由于采样技术的差异，尤其是对大体上“正常叶”的采样，可能存在诊断不足。我们队列中的低发病率有利于“偶然理论”的共同发生。由于其治疗和预后意义，这种诊断很重要。
