横纹肌样脑膜瘤临床病理观察

Rhabdoid meningioma: clinicopathological study

目的探讨横纹肌样脑膜瘤的临床病理学特征、免疫表型、超微结构和鉴别诊断要点。方法对1例横纹肌样脑膜瘤进行组织形态学、免疫组化和超微结构观察。结果患者男性,37岁。CT示左颞叶巨大肿物,手术发现肿物与硬脑膜相连。组织学显示,肿瘤主要由横纹肌样细胞组成,瘤细胞中等大,圆形或卵圆形,具有丰富的嗜酸性细胞质和偏位的细胞核,部分胞质内有包涵体,核仁易见;局部为梭形细胞型和合体细胞型脑膜瘤形态,与横纹肌样细胞有过渡。可见局灶性出血和坏死,核分裂易见。免疫组化显示肿瘤细胞为vimentin弥漫强(+),S-100(+),EMA和p53灶性(+),Ki-67阳性率为20%,actin、desmin、LCA、HMB45、GFAP、NF、AE1/AE3、CD30、CD79a、CD68、CD138、EGFR和bcl-2均(-)。超微结构显示胞质内有丰富的线粒体、溶酶体,部分细胞线粒体和溶酶体集聚在一起,在核旁形成包涵体样结构。细胞有不同程度的黏附,可见到简单连接和胞质紧密并对。结论横纹肌样脑膜瘤是一种少见的恶性肿瘤,具有侵袭性和临床进展迅速的特点,组织形态以横纹肌样细胞为主,鉴别诊断需要依靠免疫组化和超微结构检查。

Objective To investigate the clinicopathological features, immunophnotype, ultrastructure and differential diagnosis of rhabdoid meningioma. Methods One case of rhabdoid meningioma was studied by analyses of histopathologic and ultrastructual features, as well as immunohistochemistry. Results A 37-year-old man was admitted to hospital with CT examination showing a large mass with a little enhancing signal in left temporal lobe. At the operation, the mass was found to be connected to dura mater. Histopathologically, the tumor was mainly composed of rhabdoid cells that were mederately large and round or oval with abundant eosinophilic cytoplasm, eccentric nuclei, prominent nucleoli and parunuclear inclusions. The fibrous and meningothelial meningioma was found in local area where the transition from spindle cells to rhabdoid cells could be revealed. Mitoses were easily seen and the Ki67-positive cell were 20%, and also hemorrhage and necrosis were seen focally. It was positive for vimentin and S100, showed focal EMA and p53 expression. However it was negative for actin, desmin, LCA, HMB45, GFAP, NF, CD30, CD79a, CD138, CD68, EGFR and bcl-2. Ultrastructurelly, the rhabdoid cells were characterized by round nuclei with prominent nucleoli, having a lot of mitochondria and lysosomes which aggregated inclusion-like features in cytoplasm. They showed variably cohesive growth and often abutted one another. Conclusions The rhabdoid meningioma is rare and malignant tumor with aggressive behavior and rapid clinical course. The morphology of them was prominently composed of cell with rhabdoid features. Differential diagnosis should be based on immunohistechemical and ultrastructural examinations .