Delayed distant metastasis from a subcutaneous sacrococcygeal ependymoma. Case report, with tissue culture, ultrastructural observations, and review of the literature

This represents the first reported case of pulmonary metastasis from an extradural ependymoma in a subcutaneous location in the sacrococcygeal region. The nature of the metastasis was documented by tissue culture and ultrastructural examination. The embryologic basis for the occurrence of ependymomas in this region appears to be the coccygeal medullary vestige of the neural tube. Previous reports of metastasizing ependymomas include 16 which were primary in the brain, six in the cauda equina, and one in a postsacral location. Factors potentiating metastasis in these tumors include the influence of surgical intervention and longer survival from neurosurgical procedures, further enhanced by radiotherapy. The most frequent targets for metastasis from ependymomas are lungs, lymph nodes, and liver. Ultrastructural examination of the lung metastasis in this case disclosed features of both normal ependyma and choroid plexus.