Composite ganglioneuroma-paraganglioma of the filum terminale.

Extraadrenal paragangliomas are most commonly found in the carotid body and are also found with lower frequency in the CNS. These lesions are derived from the sympathoadrenal lineage of neural crest cells. Here, the authors report a rare case of a composite paraganglioma with ganglioneuromatous components found at the filum terminale in a patient who presented with a brief history of low-back pain and paresthesias in the inguinal region. Immunohistochemical analysis of the resected lesion revealed admixed elements of neuroendocrine and neuroblastoma lineages, indicating the presence of divergent differentiation of sympathoadrenal progenitor cells. This case represents a unique opportunity to understand the cell fate of sympathoadrenal progenitor cells. Here, the authors propose that paragangliomas at the filum terminale can revert to a neural crest cell precursor fate, giving rise to divergent neoplastic populations.