We report two unique cases of metaplastic ossification occurring withi
n a tubulovillous adenoma and a juvenile polyp. In both lesions, well-
formed bony spicules were present that were adjacent to living epithel
ial cells. The metaplastic bone revealed vimentin positivity and cytok
eratin negativity. The pathogenesis of osseous metaplasia in colorecta
l tumors remains unclear, but the process seems to have no clinical si
gnificance.