甲状腺呈胸腺样分化癌临床病理分析

Carcinoma showing thymus like differentiation of the thyroid:two cases report and review of literature

目的探讨甲状腺显示胸腺样分化癌(CASTLE)的临床病理特征、免疫表型和鉴别诊断。方法对2例甲状腺CASTLE进行临床资料分析、随访、病理形态学观察、免疫组化及原位杂交检测,并结合文献进行讨论。结果2例CASTLE均为女性,分别为27岁和40岁,肿块位于甲状腺下极。巨检:肿瘤灰白色,实性。镜检:肿瘤细胞呈多边形或鳞状上皮样,具有空泡状核,核仁清楚,排列成片块状、巢状或条索状,常见丰富的小淋巴细胞浸润以及纤维组织间质。例1肿瘤侵犯至甲状腺外软组织。肿瘤细胞CD5、HCK和CD117(+),部分CEA(+),TTF-1、TG、CT和CD21(-);间质淋巴细胞TdT(-)。原位杂交EBV(-)。分别于术后4个月、9个月对2例进行随访,未见复发或转移。结论CASTLE是发生于甲状腺或颈部软组织的一种少见肿瘤,多数病例预后良好。需要与转移性鼻咽癌或淋巴上皮样癌、甲状腺鳞状细胞癌和间变性癌、异位胸腺瘤、滤泡树突状细胞肿瘤等相鉴别,免疫组化检测CD5、CD117、EMA和CD21有助于鉴别诊断。

Objective To study the clinicopathologic features, immunophenotypes and differential diagnosis of carcinoma showing thymus-hke differentiation （CASTLE） of the thyroid. Methods Two cases of CASTLE were studied using the histological and immunohistochemical examinations and EBER in situ hybridization, with a review of the related literature. Results Two female patient aged 27 and 40 respectively, presented with a mass in the lower lobe of the thyroid gland. Grossly, the tumors were gray-whitish and solid. Microscopically, the tumors were composed of solid nests and sheets of polygonal or squamoid cells, which were separated by fibrous septa with small lymphocytes infiltration. The tumor cells had large vesicular nuclei with prominent nucleoli and pale cytoplasm. The invasion of adjacent connective tissue was observed in one case. Immunohistochemically, the tumor cells were positive to CD5, HCK and CD117, as well as focally positive to CEA, but negative to TG, TTF1, CY and CD21. In situ hybridization for EBER was negative in two cases. The two patients were followed up for 4 and 9 months respectively, and no local recurrence or metastasis was present. Conclusions CASTLE is a rare malignancy that occurs in the thyroid gland or in the soft tissues of the neck. The prognosis of most CASTLE tumors is favorable. It should be differentiated from metastatic nasopharygeal carcinoma or lymphoepithelioma-like carcinoma, squamous cell thyroid carcinoma, anaplastic thyroid carcinoma, ectopic thymoma and FDC tumor because these conditions have different prognosis. Immunostaining for CD5, CD117, CEA, TdT and CD21 is helpful to reach a correct diagnosis.