抄録
Three cases of small cell malignant tumors of the cerebellum from male infants were examined with light and electron microscopy and immunocytochemistry for glial fibrillary acidic protein (GFA). These studies revealed unequivocal neuronal differentiation which places these tumors into the category of so-called “cerebellar neuroblastoma” as reported by Shin et al.
Light microscopically, the tumors showed multilobulated patterns with reticulin-positive septae, not unlike those seen in so-called desmoplastic medulloblastoma. While tumor cells in the septae resembled those of a classical medulloblastoma, it was the intralobular cells that revealed ultrastructural features of neuronal differentiation. Scattered astrocytic cells and processes were also identified within the lobules by the immunoperoxidase technique for GFA. Characteristic cellular arrangements in parallel rows and fine fibrillary process formations observed light microscopically within the lobules probably represented the histologic manifestations of neuronal differentiation of the tumor.
Based on these findings, the nosologic placement of so-called “cerebellar neuroblastoma” was attempted, particularly in relation to medulloblastomas. Although histologically characteristic and ultrastructurally unique, there seemed to exist a spectrum in terms of the proportion between the neuroblastomatous area in the lobules and the medulloblastomatous area in the septae as shown in the present three cases. Therefore, the authors incline to the notion that the so-called “cerebellar neuroblastoma” is not a separate entity but a unique manifestation of neuronal differentiation occurring in medulloblastomas. However, because of the histologic resemblance, it is a distinct possibility that some of the desmoplastic medulloblastomas, especially those in younger patients, are indeed medulloblastomas showing a high degree of neuronal differentiation.
