甲状腺呈胸腺样分化癌病理观察

目的 探讨甲状腺呈胸腺样分化癌（CASTLE）的病理特征、诊断及鉴别诊断。方法 分析2例甲状腺CASTLE的临床表现,对标本进行病理学和免疫组织化学（EnVision^TM法）染色观察。结果 大体检查肿瘤呈质硬灰白色略旱分叶状肿块。光镜下肿瘤组织呈轮廓清楚的巢状,巢间可见丰富的促结缔组织增生性间质。肿瘤细胞呈多边形或梭形,胞质轻度嗜酸,核卵圆形,呈空泡状,有清楚的小核仁,核异型性较轻,核分裂象1～2／10HPF。免疫组织化学肿瘤细胞表达CD5及CD117。结论 CASTLE是一种少见的甲状腺恶性肿瘤,有一定的病理学特征。应与甲状腺未分化癌、甲状腺鳞状细胞癌、转移性淋巴上皮瘤样癌及滤泡树突细胞肉瘤等鉴别。免疫组织化学CD5等标记对鉴别诊断有帮助。

Carcinoma showing thymus-like differentiation of the thyroid: a study of 2 cases

Objective To describe the pathologic features and differential diagnosis of carcinoma showing thymus-like differentiation (CASTLE) of thyroid. Methods The clinical findings, morphologic features and immunohistochemistry (EnVision TM) of 2 cases of CASTLE were studied. Results Macroscopically, the tumor appeared as a hard grayish-white and slightly lobulated mass. Histologic examination revealed well-circumscribed islands of tumor cells associated with desmoplastic stroma. The tumor cells were polygonal to spindle in shape and contained lightly eosinophilic cytoplasm, oval nuclei and small distinct nucleoli. The nuclear atypia was mild to moderate and the mitotic count measured 1 to 2 per 10 high-power fields. Immunohistochemical study showed that the tumor cells expressed CD5 and CD117. Conclusions CASTLE is a rare type of thyroid carcinoma with distinctive morphologic findings. It needs to be distinguished from undifferentiated thyroid carcinoma, squamous cell thyroid carcinoma, metastatic lymphoepithelioma-like carcinoma and follicular dendritic cell sarcoma. Immunohistochemical staining for CD5 and CD117 is helpful in confirming the diagnosis.