Iron localization in superficial siderosis of the central nervous system.

Originally conceived as an uncommon disorder, with the advent of MRI, CNS superficial siderosis has been observed more frequently. We present histologic, histochemical, immunohistochemical, immunofluorescent and ultrastructural evaluation of a 56-year-old woman with superficial siderosis. Iron was concentrated in macrophages, superficial astrocytes and gray matter oligodendroglia deep within the cord. While spatially associated with dystrophic glial and neuronal spheroids, iron did not colocalize with mitochondria. Neurotoxic effects were observed despite selective iron localization only within a variety of non-neuronal cell types.