Extraneural Metastasis in Cerebellar Medulloblastomas

This paper deals with the clinicopathological findings in two cases of cerebellar mudulloblastoma with extraneural metastasis. These two cases fulfill Weiss' minimal criteria for confirmation of extraneural metastasis of a glioma. The first case was an 18 month-old boy with a 14 month clinical history. A ventriculoperitoneal shunt was performed, followed by three series of Linac irradiations, for a total dose of 13, 750 rads. An autopsy revealed a cerebellar vermis tumor accompanied by ventricular and spinal subarachnoidal seeding. Milliary metastatic nodules were noticed macroscopically in the liver, and microscopic deposits were also recognized in the right ventricular wall of the heart, pericardium, lumbar vertebrae, capsules of the pancreas and spleen, and adipose tissue surrounding the adrenal gland. Tumor cell invasion in a small vein within the vermis tumor was thought to be a cause of blood-stream metastases. The second case was a 10 year-old boy with a clinical history of 16 months. The cerebellar vermis tumor was partially removed and a ventriculoperitoneal shunt was performed at the same time. The patient was given radiotherapy, 4, 000 rads in the whole brain, 4, 000 rads in the upper spinal canal and 3, 000 rads in the lower spinal canal. One month later he felt pain in the hip joint and lower back. Radiography showed osteolytic changes in the pelvis and femoral bone, and later in the humerus, ribs and scapulas. Local irradiation of bony metastase was effective for a while. An autopsy revealed a small tumor remnant in the cerebellar vermis accompanied by spinal subarachnoidal seeding. Systemic bony metastasis was confirmed with no metastasis to the internal organs and lymphoid tissues. The dura mater at the primary site of the tumor was invaded by tumor cells, and this seemed to be the route of blood-spread metastasis. Approximately 80 cases of cerebellar medulloblastoma with extraneural metastasis have been reported in assorted report. The mode and site of metastasis, diagnosis and treatment are critically reviewed in this paper.