Banded structure in solitary trichoepithelioma.

Electron microscopical observations were made in a case of solitary trichoepithelioma. Enlarged ERs were found in the tumor cells, showing a peculiar structure with fine granules and an electron-dense banded structure, about 50 nm wide respectively, lying at intervals of 250 nm. In addition to this structure, dense ovoid bodies, about 500 to 600 nm in diameter, were also observed.