不典型毛细胞型星形细胞瘤MRI表现

目的探讨不典型毛细胞型星形细胞瘤的MRI特点。方法对经病理证实的22例不典型毛细胞型星形细胞瘤（其中毛粘液样星形细胞瘤3例）的临床资料、MRI及病理表现进行对照分析。结果临床：本组22例病例中，2．5岁1例，20岁以上7侈9，其中36岁、38岁、46岁各1例。部位：病灶多发1例，病灶位于大脑半球7例，鞍区5例，脊髓4例。MRI：7例不典型性毛细胞星形细胞瘤呈实性，MRI表现等长T1、长T2信号，可见微囊变，增强后实性部分多均匀强化，囊变区未见强化；弥漫性3例，表现为边界不清，混杂性长T1、长T2信号，增强后强化不明显。22例病例中WHOⅠ级的毛粘液样星形细胞痛3例，MRI表现为实性病灶，1例边界不清，1例多发，2例出现瘤周水肿，增强后病灶不强化或不均匀强化：病理：3例毛细胞型星形细胞瘤镜下表现为多数瘤细胞形态似少突细胞，呈蜂窝状排列；3例毛粘液样星形细胞瘤镜下表现为粘液样背景下细胞密度高，细胞核多为大小不等，多数细胞异型性明显。结论不典型毛细胞型星形细胞瘤可发生于成人、可多发、可发生于鞍区及延髓，MRI可呈实性表现，WHOⅡ级毛粘液样星形细胞瘤在影像与临床更是有恶性表现。

MRI Manifestations of Atypical Pilocytic Astrocytoma

Objective To analyze the MR imaging features of atypical piloeytic astrocytoma.Methods The MRI imaging,clinical and pathological data of 22 patients with pilocytic astrocytoma,3 of them are pilomyxoid astrocytoma,were reviewed retrospectively.All cases were proved by surgery and pathological examinations.Results Clinic:Among all the cases,1 case was 2.5 years old,7 cases were more than 20 years old,and 1 case was 36,38 and 46 years old respectively.Sites Of 22 cases,1 case had multiple lesions;lesions of 7 cases were at cerebral hemisphere,5 cases at sellar region;4 cases at spinal cord.MRI:7 cases with atypical pilocytic astrocytoma performed as solid masses.MRI images showed iso-or long Tl and long T2 signalL and multiple microcysts could be foundL After contrast enhancement,the solid part showed uniform enhancement,while the cystic part showed non-enhancement;3 cases showed diffuse leisions,obscure boundary,heterogeneous long Tl and long T2 signal and non-enhancement.3 of 22 are WHO Ⅱ pilocytic astrocytoma.MRI showed solid lesions.1case had obscure boundary.1 case had diffuse lesions.2 cases showed peritumoral edema.After constrast enhancement,the mass showed non-enhancement or inhomogeneous enhancement.Pathology:The endoscopic findings of 3 cases with pilocytic astrocytoma showed oligodendrocyte,and arranged as honeycomb;The endoscopic findings of 3 cases with pilomyxoid astrocytoma showed formyxoid background and high cell density,and the nucleus were inequality of size,and most cellular showed obvious atypia.Conclusion Atypical piloeytic astrocytoma could occur in adult,has multiple lesions,locates in sellar region or medulla oblongata,and MRI could show solid mass.WHO Ⅱ pilocytic astrocytoma could show malignant features in MRI images and clinics.