Paraganglioma of the cauda equina: a report of two cases with unusual histopathological features.

Paragangliomas of the cauda equina are very rare. Preoperatively, they are usually diagnosed as schwannoma. We report 2 cases that exhibited unusual histopathologic structure as well as a typical Zellballen pattern with a highly vascular stroma. The unusual features included papillary, ribboning, and pseudorosette patterns, ganglion cell nests, and melanin pigment. Pathological diagnosis of paraganglioma may be especially difficult when such unusual histopathological features are seen. Correct histopathological diagnosis is important as paraganglioma has a better prognosis than other tumors included in the differential diagnosis for this location.