背景:CIC重排肉瘤(CRS)代表了属于尤因样肉瘤家族的未分化小圆细胞肉瘤的新实体。CRS是最常见的类型。CIC基因的融合伴侣包括DUX4,FOXO4和最近识别的NUTM1。最近有报道称,儿科患者中罕见的CIC::NUTM1肉瘤发生在大脑中,肾,骨头,和软组织。然而,这种情况尚未在四肢的软组织中发现。
方法:我们报告了一例位于一名18岁男性右上肢的CIC::NUTM1肉瘤。肿瘤表现出CIC::DUX4肉瘤的典型形态特征,小到中等大小的圆形细胞,小叶图案,局灶性纺锤体,粘液样基质,和斑片状坏死。肿瘤弥漫性表达NUTM1,在弱至中等强度时WT1cter呈阳性,CD99呈局部阳性,而角蛋白呈阴性,EMA,P40,MyoD1,肌原蛋白,NKX2.2,BCOR,和泛TRK。荧光原位杂交分析显示CIC和NUTM1基因裂解。
结论:CIC::NUTM1肉瘤代表了一种新的CRS分子变异,对中枢神经系统和较年轻的儿科患者具有偏好。其形态和表型可能被误认为是NUT癌,行为比其他形式的CRS更进步。对于这种罕见的新发现的基因融合变体,在未分化肿瘤的诊断中,有必要将分子和免疫组织化学结果与形态学特征相结合。
BACKGROUND: CIC-rearranged sarcomas (CRS) represent a new entity of undifferentiated small round cell sarcoma belonging to the Ewing-like sarcomas family. CRS are the most common type. Fusion partners for the CIC gene include DUX4, FOXO4, and the recently recognizedNUTM1. Rare cases of CIC::NUTM1 sarcoma in pediatric patients have recently been reported in brain, kidney, bone, and soft tissues. However, such cases have not been identified in the soft tissues of the limbs.
METHODS: We reported a
case of CIC::NUTM1 sarcoma located in the right upper limb of an 18-year-old man. The tumor displayed morphologic features typical of CIC::DUX4 sarcomas, with small- to medium-sized round cells, a lobular pattern, focal spindling, myxoid stroma, and patchy necrosis. The tumor diffusely expressed NUTM1, was positive for WT1cter at weak to moderate intensity, and was focally positive for CD99, while it was negative for keratins, EMA, P40, MyoD1, myogenin, NKX2.2, BCOR, and pan-TRK. Fluorescence in situ hybridization analyses revealed cleavage of the CIC and NUTM1 genes.
CONCLUSIONS: CIC::NUTM1 sarcomas represent a novel molecular variant of CRS with a preference for the central nervous system and younger pediatric persons. Its morphology and phenotype may be mistaken for NUT carcinomas, and the behavior is more progressive than other forms of CRS. For this rare and newly discovered gene fusion variant, it is necessary to integrate molecular and immunohistochemical findings with morphologic features in the diagnosis of undifferentiated neoplasms.