Oncocytic transformation of choroid plexus epithelium.

In a 27-year-old woman who died of Leigh's disease, adult form, autopsy revealed in addition to the usual morphological changes of that condition, marked oncocytic transformation of choroid plexus epithelium in all cerebral ventricles: the cytoplasm of epithelial cells was enlarged, eosinophilic, and filled with fine granules. By electron microscopy the granules were identified as closely packed mitochondria that appeared to proliferate at the expense of other cytoplasmic organelles. This appears to be the first report of oncocytic transformation involving the epithelium of the choroid plexus. The relationship between the oncocytic changes and the patient's underlying Leigh's disease remains speculative at this time.