毛细胞型星形细胞瘤(pilocyticastrocytoma,PA),属于神经上皮肿瘤中星形细胞起源肿瘤的亚型,是一种少见的良性肿瘤,由Penfield于年根据肿瘤细胞两端见细长的毛发样胶质纤维丝而命名。年和年版WHO中枢神经系统肿瘤组织学分类标准中均列为I级星形细胞肿瘤。
Pilocyticastrocytoma(PA),asubtypeofastrocyte-derivedneoplasmsinneuroepithelialtumors,isararebenignneoplasm.ItwasnamedbyPenfieldinforthepresenceoflonghair-likeglialfilamentsatbothendsoftheneoplasticcells.TheWHOCentralNervousSystemTumorHistologicalClassificationStandards(andeditions)areclassifiedasGradeIastrocytictumors.
PA占颅内肿瘤的1.9%,约占原发性中枢神经系统肿瘤的1.5%,好发于儿童和青少年,多数在20岁之前发病,在4岁左右出现发病高峰,随年龄增长发病率有下降趋势,45岁以上成年人发病率不足1/万,男女发病比率无明显差异。PA可起源于整个神经轴的任何位置,但好发于小脑视交叉、下丘脑、视神经等部位,也可以发生在脑干、大脑半球、基底节及脊髓,其中发生于视交叉、下丘脑、视神经的PA常伴有神经纤维瘤病1型(Neurofibromatosis1,NF1)。视路胶质瘤有两种存在形式,一种独立存在,另一种为NF1相关型,前者更为常见,后者约占视路胶质瘤的30%。NF相关型视路胶质瘤是NF1患者最常见的脑肿瘤,其发病率为15%-50%,发病高峰在2-8岁之间。脑干胶质瘤可简单地分为弥漫性浸润性胶质瘤和局灶性胶质瘤,而局灶性胶质瘤主要为PA,大多数儿童PA都位于幕下,特别是小脑(60%)
PAaccountedfor1.9%ofintracranialtumorsand1.5%ofprimarycentralnervoussystemtumors.Mostofthemoccurredinchildrenandadolescentsbeforetheageof20andpeakedaroundtheageof4.TheincidenceofPAdeclinedwithage.Theincidencerateofadultsover45yearsoldwaslessthan1/1million.Therewasnosignificantdifferencebetweenmaleandfemale.PAcanoriginatefromanypartofthewholenerveaxis,butitispredominantincerebellumopticchiasm,hypothalamus,opticnerve,etc.Itcanalsooccurinbrainstem,cerebralhemisphere,basalgangliaandspinalcord.PAoccurringinopticchiasm,hypothalamusandopticnerveisoftenac