[CIC-rearranged sarcoma: a clinicopathological analysis of four cases].

Objective: To investigate the clinicopathological features and differential diagnosis of CIC-rearranged sarcoma (CRS). Methods: Five CRSs of 4 patients (2 biopsies of pelvic cavity and lung metastasis from case 4) diagnosed in the First Affiliated Hospital of Nanjing Medical University were enrolled from 2019 to 2021. All cases were evaluated by clinical presentation, H&E, immunohistochemical staining and molecular analysis and the related literature was reviewed. Results: There were one male and three females, the age at diagnosis ranged from 18 to 58 (mean 42.5) years. Three cases were from the deep soft tissues of the trunk and one case from the skin of foot. Grossly, the tumor size ranged from 1 to 16 cm. Microscopically, the tumor was arranged in nodules or solid sheets. The tumor cells were typically round or ovoid, with occasional spindled or epithelioid morphology. The nuclei were round to ovoid with vesicular chromatin and prominent nucleoli. Mitotic figures were brisk (>10/10 HPF). Rhabdoid cells were seen in four of five cases. Myxoid change and hemorrhage were observed in all samples and two cases showed geographic necrosis. Immunohistochemically, CD99 was variably positive in all samples, while WT1 and TLE-1 were positive in four of five samples. Molecular analysis showed CIC-rearrangements in all cases. Two patients succumbed within 3 months. One had mediastinal metastasis 9 months after surgery. One underwent adjuvant chemotherapy and remained tumor-free 10 months after diagnosis. Conclusions: CIC-rearranged sarcoma is uncommon and shows aggressive clinical course with dismal prognosis. The morphological and immunohistochemical characteristics can largely overlap with a variety of sarcomas; hence, knowledge of this entity is vital to avoid potential diagnostic pitfalls. Definitive diagnosis requires molecular confirmation of CIC-gene rearrangement.目的： 探讨CIC重排肉瘤（CIC-rearranged sarcoma，CRS）的临床病理学特征及鉴别诊断。 方法： 收集南京医科大学第一附属医院2019—2021年诊治的CRS患者4例，组织样本5例（例4为盆腔及肺转移瘤穿刺2份样本），对其临床表现、组织学形态、免疫表型及分子遗传学进行分析总结，并复习文献。 结果： 4例患者男性1例，女性3例，平均年龄42.5岁（18~58岁），躯干深部软组织3例，足趾皮肤1例。大体检查手术切除标本肿瘤最大径1~16 cm，切面灰红灰白，质软。镜下观察手术切除标本肿瘤呈多结节状或弥漫片状排列，肿瘤细胞以圆形或卵圆形细胞为主，梭形细胞和上皮样细胞多见，4例样本可见横纹肌样细胞。核圆形、卵圆形或不规则形，核空泡状，核仁明显，核分裂象>10个/10 HPF。间质均见黏液变性及大片出血，2例可见地图样坏死。免疫表型，CD99不同程度阳性（5/5），WT1、TLE-1阳性（4/5）。分子遗传学，5例均检测到CIC基因断裂重组。随访患者2例诊断后3个月内死亡；1例术后9个月纵隔转移，再次术后2个月无瘤存活；1例术后行辅助化疗，首次诊断后10个月无瘤存活。 结论： CRS罕见，临床呈高度侵袭性，预后极差，其病理形态及免疫组织化学与多种肉瘤重叠，应注意识别免疫组织化学交叉陷阱，确诊需行分子遗传学证实CIC基因重排。.