伽玛刀治疗颅内肿瘤的病理组织学研究

Histopathological investigation on intracranial tumors after Gamma Knife radiosurgery

目的观察伽玛刀治疗颅内肿瘤的病理组织学变化,探讨伽玛刀治疗的放射生物学效应机制。方法对46例颅内肿瘤伽玛刀照射后的手术标本行光镜、电镜的病理形态学变化观察,并采用S-P法对上述肿瘤标本和10例正常脑组织血管标本行免疫组织化学染色,观察受照射肿瘤血管的CD34、α-SMA的表达,根据染色强度行对比分析。结果伽玛刀照射后的肿瘤细胞均有不同程度的凝固性坏死,肿瘤间质纤维化,血管内皮细胞肿胀、固缩、脱落,内皮增生,肿瘤血管扩张、充血,血管壁普遍出现增厚,管腔闭塞。可伴有炎性细胞浸润或出血。肿瘤的周边区域可观察到早期凋亡细胞。免疫组化的结果显示正常脑组织血管中CD34、α-SMA明显呈阳性,而受照射的肿瘤组织中CD34的反应性明显减少或呈阴性。α-SMA在大多数肿瘤组织中仍呈强阳性反应。结论伽玛刀治疗颅内肿瘤的放射生物学效应机制主要为肿瘤细胞的直接杀伤效应与血管效应的双重作用;伽玛刀照射诱导肿瘤细胞凋亡在伽玛刀治疗中起到一定作用。

Objective To observe the histopathological changes of intracranial tumors treated with Gamma Knife radiosurgery and to evaluate the radiobiological effect of Gamma Knife radiosurgery on brain tumors. Methods 46 operative intracranial tumor specimens undergone Gamma Knife radiosurgery previously were observed morphologically by light and electron microscopy. These tumor specimens and 10 normal cerebral vessel samples were stained immunohistochemically with CD34 and α-SMA respectively to study the tumor vascular progressive effects of the irradiation. A comparison analysis was made in the expression intensity. Results The coagulation necrosis of various degrees occurred in the tumor cells, and an increasing of fibrous stroma was observed with fibrous thickening and fibrinoid necrosis. The tumor vascular endothelial cells underwent swelling, loss and compensatory proliferation after irradiation. The fibrous thickening of the vascular walls was observed, following with marked lymphocyte infiltration and hemorrhages. However, the apoptosis cells were observed in the peripheral tumor field, which received the lower dose of radiation. The CD34 and α-SMA were expressed significantly in the normal control brain vessel tissues in a manner of obvious and continuous staining. In the irradiated target tumor tissue samples, CD34 reactions decreased remarkably, but α-SMA was expressed markedly in most of the tumor specimens. Conclusion The cytoxicity of ionizing radiation and the vessel radioreaction in the tumor tissue both play important roles in killing tumor cells after Gamma Knife therapy. The Gamma irradiation-induced apoptosis may be a possible mechanism in reducing tumor size following Gamma Knife radiosurgery.