Mikami Y, Hidaka T, Akisada T, Takemoto T, Irei I, Manabe T
Departments of Pathology and; Otorhinolaryngology, Kawasaki Medical School Hospital, Kurashiki, Okayama, Japan.
Pathol Int. 2000 Feb;50(2):156-61. doi: 10.1046/j.1440-1827.2000.01019.x.
A rare example of malignant transformation in an ancient schwannoma arising in the right side of the neck of a 51-year-old man without any clinical manifestations suggesting neurofibromatosis is described. The tumor, approximately 4 cm at its largest dimension, was well circumscribed and had a direct connection with the sympathetic nerve. Microscopically, the central portion of the tumor showed features of ancient schwannoma characterized by extensive hyalinization with cystic degeneration, scattered spindle cells with hyperchromatic and tapered nuclei, and some symplastic changes. However, predominantly in the outer portion, a proliferation of spindle-shaped cells with enlarged nuclei was present. The nuclei of these cells showed irregular contours, coarse granular chromatin texture, and conspicuous nucleoli. Mitotic figures and small necrotic foci with scattered apoptotic bodies were also seen. Immunohistochemically, S-100 protein was almost negative in areas consisting of overtly atypical cells where the mitotic index evaluated with MIB-1 antibody was 30.5%. In contrast, S-100-positive bland spindle cells were scattered in an extensively hyalinized area with a labeling index less than 3%. P53 protein was strongly positive in atypical spindle cells. Although it is a very uncommon event, definite nuclear atypia, frequent mitotic figures, and the existence of small necrotic foci should be recognized as indicating a diagnosis of malignant degeneration of benign schwannoma. Immunohistochemistry would be useful as an ancillary technique in such a setting.
本文描述了一例罕见的恶性转化病例，发生于一名51岁男性右侧颈部的古老型神经鞘瘤，该患者无任何提示神经纤维瘤病的临床表现。肿瘤最大直径约4 cm，边界清晰，与交感神经直接相连。显微镜下，肿瘤中央部分呈现古老型神经鞘瘤的特征，表现为广泛的玻璃样变伴囊性变、散在的核深染且呈锥形的梭形细胞以及一些化生改变。然而，主要在肿瘤外部，出现了核增大的梭形细胞增殖。这些细胞的核轮廓不规则，染色质呈粗颗粒状，核仁明显。还可见到有丝分裂象以及散在凋亡小体的小坏死灶。免疫组化显示，在由明显非典型细胞组成的区域，S-100蛋白几乎呈阴性，用MIB-1抗体评估的有丝分裂指数为30.5%。相比之下，S-100阳性的梭形细胞散在于广泛玻璃样变区域中，标记指数小于3%。P53蛋白在非典型梭形细胞中呈强阳性。尽管这是一个非常罕见的事件，但明确的核异型性、频繁的有丝分裂象以及小坏死灶的存在应被视为提示良性神经鞘瘤恶性变的诊断依据。免疫组化在这种情况下作为辅助技术将很有用。
