Giant mitochondria with paracrystalline inclusions in paraganglioma of the urinary bladder: correlation with mitochondrial abnormalities in paragangliomas of other sites.

Mitochondrial abnormalities have received relatively little attention in the ultrastructural evaluation of paragangliomas. Review of the few literature references dealing with this issue, however, reveals that quantitative and qualitative changes of these organelles occur in that context. A bladder paraganglioma is described that was characterized by numerous mitochondria, which in addition displayed giant forms along with matrical paracrystalline inclusions. Upon retrospective review of 12 archival cases of paragangliomas, enlarged and structurally abnormal mitochondria were found in all of them. Although various speculations can be made, the mechanism of formation and the pathophysiologic significance of these abnormal mitochondria remain unknown. From a morphologic diagnostic point of view, however, these abnormalities, which in this case of bladder paraganglioma were also light microscopically evident, can be of significant help in establishing the correct diagnosis.