硬化性横纹肌肉瘤的临床病理学分析

Sclerosing rhabdomyosarcoma:a clinicopathologic study of four cases with review of literature

目的探讨硬化性横纹肌肉瘤(SRMS)的临床病理学特征,以及与胚胎性横纹肌肉瘤(ERMS)和腺泡状横纹肌肉瘤(ARMS)之间的关系。方法观察4例 SRMS 的临床特点、光镜形态,以免疫组织化学染色[En Vision 法;波形蛋白、结蛋白、α-平滑肌肌动蛋白(α-SMA)、肌特异性肌动蛋白(MSA)、生肌蛋白、肌调节蛋白(Myo D1)、高分子量钙调结合蛋白(h-CALD)、CD31、CD34、第Ⅷ因子相关抗原、S-100蛋白、细胞角蛋白(AE1/AE3)和间变性大细胞淋巴瘤激酶(ALK1)]确定免疫学表型。结果 4例均发生于成年人,平均年龄41.5岁。男性2例,女性2例。肿瘤分别位于左腕部、右大腿、右颊部和右面部,直径大小为2.5～10.0 cm,平均5.7 cm。镜下以含有大量玻璃样变的基质为特征,类似原始的骨样组织或软骨样基质。瘤细胞主要由原始的小圆形细胞组成,其排列方式呈多样化,包括条束状、索状、列兵样、梁状、微腺泡状和假血管样排列等。除1例可见少量的横纹肌母细胞外,其余3例均未见横纹肌母细胞,也未见花环状多核巨细胞。2例的局部区域还含有梭形细胞成分,其中1例类似梭形细胞横纹肌肉瘤,另1例类似周围神经肿瘤。免疫组织化学标记显示,瘤细胞弥漫强阳性表达 Myo D1,而结蛋白多为灶性表达,生肌蛋白多为阴性或仅为灶性阳性。3例表达MSA,2例表达α-SMA,但不表达 h-CALD。S-100蛋白、CD31和 ALK1等标记均为阴性。结论 SRMS在形态上和免疫学表型上与 ERMS 和 ARMS 均有所不同,但在细胞遗传学上与 ERMS 关系密切。熟悉 SRMS 的形态特征和免疫学表型有助于识别这种少见的横纹肌肉瘤亚型及与其他硬化性肿瘤相鉴别。

Objective To study the clinicopathologic characteristics of sclerosing rhabdomyosarcoma （SRMS） and its distinction from embryonal rhabdomyosarcoma （ERMS） and alveolar rhabdomyosarcoma （ARMS）. Methods The clinical, histologic and immunohistochemical features of 4 cases of SRMS were studied. The literature was reviewed. Results All the 4 cases occurred in adults. The age of patients ranged from 20 to 54 years （ mean = 41.5 years）. The male-to-female ratio was 1：1. The tumor was located in the left wrist, right thigh, right face and right cheek respectively and the tumor size varied from 2.5 cm to 10 cm in dimension （ mean = 5.7 cm）. Histologically, SRMS was characterized by the presence of large amounts of heavily hyalinized matrix, mimicking osteoid or chondroid tissue. The tumor cells were composed predominantly of primitive small round cells which were arranged in diverse growth patterns, including fascicular, cord-like, single-file, trabecular, microalveolar and pseudovascular structures. A few rhabdomyoblasts were identified in 1 case. A second spindle cell component was focally found in 2 cases, resembling spindle cell rhabdomyosarcoma or peripheral nerve sheath tumor. Immunohistochemically, all cases showed diffuse staining for Myo D1 and focal staining for desmin. The staining for myogenin was often negative. Three of the cases also expressed muscle-specific actin and 2 cases were positive for or-smooth muscle actin. They were all negative for h-caldesmon, S-100 protein, CD31, CD34, AE1/AE3 and anaplastic lymphoma kinase protein. Conclusions SRMS differs from ERMS and ARMS morphologically. Recent cytogenetic studies however suggest a histogenetic relationship with ERMS. Familiarity with its morphologic features and immunophenotype may help to distinguish this peculiar variant of rhabdomyosarcomafrom a variety of lesions with abundant sclerosing matrix.