Koeller Kelly K, Rushing Elisabeth J
Department of Radiologic Pathology, Armed Forces Institute of Pathology, 14th St at Alaska Ave, Bldg 54, Washington, DC 20306-6000, USA.
Radiographics. 2003 Nov-Dec;23(6):1613-37. doi: 10.1148/rg.236035168.
Medulloblastoma is the most common pediatric central nervous system malignancy and the most common primary tumor of the posterior fossa in children. This highly malignant neoplasm occurs more frequently in males and usually before 10 years of age. Clinical symptoms and signs are generally brief, typically less than 3 months in duration, and reflect the strong predilection of this tumor to arise within the cerebellum, most often in the vermis. Although much less common, the disease may also occur in adults, usually in the 3rd and 4th decades of life. Surgical resection, radiation therapy, and chemotherapy have substantially lowered the mortality associated with this tumor, with 5-year survival rates now commonly well above 50%. Still, both dissemination at the time of diagnosis and recurrence remain obstacles in achieving a cure. The tumor has characteristic hyperattenuation on unenhanced computed tomographic scans that reflects the high nuclear-cytoplasmic ratio seen at histologic analysis. The tumor typically appears heterogeneous on images, findings that are related to cyst formation, hemorrhage, and calcification and that are even more pronounced with magnetic resonance (MR) imaging. Evidence of leptomeningeal metastatic spread is present in 33% of all cases at the time of diagnosis and is well evaluated with contrast-enhanced MR imaging of the brain and the spine. Although controversial, postoperative surveillance with MR imaging is performed at most institutions in the hope of facilitating a better outcome. With continued research, treatment of these common neoplasms should improve, perhaps even achieving a cure in the future.
髓母细胞瘤是儿童最常见的中枢神经系统恶性肿瘤，也是儿童后颅窝最常见的原发性肿瘤。这种高度恶性的肿瘤在男性中更常见，通常发生在10岁之前。临床症状和体征一般持续时间较短，通常少于3个月，反映出该肿瘤极易起源于小脑，最常见于蚓部。虽然这种疾病在成人中较少见，但也可能发生，通常在30至40岁之间。手术切除、放射治疗和化疗已大幅降低了与该肿瘤相关的死亡率，目前5年生存率普遍远高于50%。然而，诊断时的播散和复发仍然是实现治愈的障碍。该肿瘤在未增强的计算机断层扫描上具有特征性的高密度影，这反映了组织学分析中所见的高核质比。肿瘤在影像上通常表现为不均匀，这些表现与囊肿形成、出血和钙化有关，在磁共振成像上更为明显。在所有病例中，33%在诊断时存在软脑膜转移扩散的证据，通过脑和脊柱的对比增强磁共振成像可以很好地评估。尽管存在争议，但大多数机构仍进行术后磁共振成像监测，希望能促进更好的治疗效果。随着持续研究，这些常见肿瘤的治疗应该会有所改善，也许未来甚至能实现治愈。
