杨守京  空军军医大学（第四军医大学）西京医院病理科, 西安 710032

      横纹肌肉瘤 (Rhabdomyosarcoma, RMS) 是常见的一种软组织恶性肿瘤，分为胚胎性、腺泡状和多形性横纹肌肉瘤3种组织学亚型，胚胎性RMS多见于儿童，腺泡状RMS多发生于青少年，而多形性RMS多见于中老年患者，其预后比前两者差。梭形细胞/硬化性横纹肌肉瘤(Spindle cell/sclerosing rhabdomyosarcoma, SRMS)是一种以梭形细胞为主的RMS，于1992年被描述, 以往被认为是胚胎性横纹肌肉瘤的少见亚型，好发于儿童和青少年的睾丸旁，其次为头颈部，预后比其他胚胎性RMS相对较好。成人SRMS比较少见，Rubin等在1998年首次描述了发生于成人的SRMS，其有更加侵袭性的临床经过。由于其临床表现及预后不同于其它类型，在最新WHO分类中SRMS被列于单独的类型 。新近发现，约有50%的该类型肿瘤，有MyoD1 L122R基因突变，与野生型相比，具有更高的侵袭性和预后，因而被认为是SRMS中的一个亚型。
    作者收集了自2010年至今的19例SRMS病例，包括12例儿童和7例成人SRMS，分析总结其临床病理学特征和免疫表型，并进行MyoD1基因突变检测，探讨SRMS的临床病理学特征、免疫表型，诊断及鉴别诊断，旨在提高对该肿瘤的认识。结果 19例患者中10例男性，9例女性。年龄8个月~85岁，平均22岁。发生于头颈部7例，腹腔4例，这两个部位占总数58%，其它部位分别为盆腔2例，左肩部2例，左前臂1例，背部1例，右腋下1例，右肱骨1例。病人临床主要表现为逐渐增大的肿块。肿块直径2.5~20 cm，平均5.6 cm。组织学上肿瘤主要由梭形细胞组成，呈鱼骨样或人字形的束状排列，似成人型纤维肉瘤；有时在梭形细胞之间有少量的梭形或多角形的横纹肌母细胞。其中4例局部区域可见明显的间质硬化，2例局灶区域可见血管外皮细胞瘤样结构，4例出现疏松黏液样区域，9例可见不同程度的坏死灶。免疫组织化学显示，梭形细胞均desmin，Myogenin和MyoD1中至少有2项不同程度阳性；而其它标记物，如CD34, AE1/AE3, HMB-45, SMA, H-cald和S-100均阴性。11例进行了MyoD1基因突变检测，3例（3/11，27%）检测到L122R位点突变。获取随访信息11例，时间1个月-51个月，3例因多发转移死亡，3例复发，1例带瘤生存。
    因SRAM的预后和治疗方式与其它类型梭形肿瘤不同，在临床病理诊断中，需要与发生于儿童以及成人具有梭形细胞形态的肿瘤，如纤维瘤病、纤维肉瘤、纤维性错构瘤、平滑肌肉瘤肌、纤维母细胞肉瘤、 恶性外围神经鞘瘤伴有肌源性分化（蝾螈瘤）、滑膜肉瘤,  以及其它梭形细胞肿瘤鉴别。其中免疫组化检测MyoD1, Myogenin, MyoD1, 及MyoD1基因检测是关键。
    SRMS属少见类型的横纹肌肉瘤，儿童多见，而成人较少见。该肿瘤好发于头颈部，伴有MyoD1基因突变的SRMS，更具有侵袭性的生物学行为。

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