本站原创[关 键 词 ] 间质瘤, 小网膜
[中图分类号] R735.4 [文献标识码] A [文章编号] 1673-9701(2010)13-100-02
胃肠道间质瘤(GIST)少见,而原发于小网膜的间质瘤更为少见,我们收治1例,现并文献复习报道如下.
1.临床资料
患者,男,62岁,发现腹部肿物10d入院.该患者于10d前体检过程中通过磁共振证实腹腔肿物,无发热,无腹痛、腹胀,无恶心、呕吐,排气、排便如常.近期体重未见减轻.查体:腹平坦,未见肠型及蠕动波,未触及肿物,全腹无压痛及肌紧张.辅助检查:MRI:小网膜区可见囊实性占位病变,囊性部分呈T1WI低、T2WI高信号,实性部分大致呈等信号,范围约为3.2cm×2.2cm,部分边界不清,静注Gd-DTPA增强扫描后,小网膜区占位病变动脉期及门脉期未见强化,延迟期可见边缘明显结节状强化,印象诊断:小网膜区占位,考虑间叶组织源性肿瘤,见图1、2.术前诊断:小网膜肿物,于入院后3d在全麻下行剖腹探查术,术中见小网膜近小弯处一大小约5cm×5cm×5cm球形肿物,包膜完整,与胰腺及胃小弯部分粘连,血运主要来自胃小弯血管分支.探查腹腔内未见其他肿物.术中切除肿物顺利.术后病理回报:瘤组织由梭形细胞构成,编织状排列,核杆状,有异型性,核分裂(0-1)个/10HPF.病理诊断:免疫组化:CD117(+),CD34(+),vimentin(+),A(-),ki67(+<5%),见图3~7,(小网膜)间质瘤.术后6d痊愈出院.
2.讨论
目前认为间质瘤起源于胃肠道间质细胞(interstitial cells of Cajal ICCs)或其前体[1],可发生于胃肠道中ICCS存在的任何位置,它常起源于胃(40%～60%)、小肠(30%～40%)、直肠肛门(7%)、结肠和食管等[2,3],仍可发生于腹腔内组织,如大网膜、肠系膜、子宫内膜等,但发生病例很少[4-6].
流行病学调查,胃肠间质瘤(gastrointestinal stromal tumor,GIST)的病例报道很少.其发病平均年龄为60岁,男性病例略多于女性.而小网膜间质瘤更加稀少.经统计,其平均发病年龄为64岁,与胃肠间质瘤的发病年龄相似.病例报道最年轻患者,仅22岁[7].我们报道的患者62岁,恰位于平均年龄之间.
Miettinen等报道胃肠间质瘤发病仅有3%小于21岁,其甚少发生于儿童[8].Hayashi等比较成人与儿童GIST患者发现:GIST在儿童中好发于女性,而且与成人比较发生转移率低[9].小网膜间质瘤镜下特点与潜在恶性的胃肠间质瘤一致.不同于典型平滑肌瘤和神经鞘瘤[10],其外周常有固定薄膜包绕,内为多房囊性.囊性部分常被凝结血块和坏死组织填充,外周坚硬成分常由均匀延展的梭形细胞交错形成.这些梭形细胞的核常呈1～3个核分裂/50HPF.这些特征表明间质瘤呈中性而非肌原性.免疫组化:S-100 蛋白、髓鞘碱性蛋白、平滑肌特异性肌动蛋白和dein阴性,vimentin和CD34阳性.免疫组化特点与胃肠道间质瘤特点一致[11,12].本例患者病理回报:瘤组织由梭形细胞构成,编织状排列,核杆状,有异型性.免疫组化:CD117(+),CD34(+),vimentin(+),ki67(+<5%).故诊断为小网膜间质瘤.间质瘤可根据核分裂数及肿瘤大小来判断良恶性:核分裂数<2为良性,良恶交界为2～5,>5/10HPF为恶性.核分裂静止期上皮性肿瘤直径≥6时为恶性[13].由于小网膜间质瘤较少发生,故其良恶性的判断标准尚未制定.既往间质瘤的治疗以手术切除为主,化疗对间质瘤的治疗效果并不满意[14].近些年伊马替尼(酪氨酸激酶抑制剂)逐渐应用于间质瘤的化学治疗,并取得一定治疗效果[15].而对于发生于小网膜的间质瘤而言,手术切除是目前治疗的最有效方法.发生于小网膜的间质瘤对化学治疗是否敏感,仍有待于进一步临床研究.据报道,肿瘤大小、细胞结构、有丝分裂计数、组织学分型、远处转移、浸润程度和坏死程度等因素影响着胃肠道间质瘤的愈后[11].这些因素可能也同样影响小网膜间质瘤的愈后.由于小网膜间质瘤较为少见,故对于其治疗及愈后相关因素尚无定论,有待于进一步临床研究证明.
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(收稿日期:2010-02-26)
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