Clear cell change in colorectal adenomas: its incidence and histological characteristics

The aim of our investigation was to clarify the histological characteristics and biological significance of clear cell change in colorectal adenomas. METHODS ANID RESULTS: We found three cases (0.086%) of tubular adenomas with clear cell change in a review of 3486 cases of colorectal adenoma. These three cases occurred in male patients and were located in the left-sided colon. To investigate the nature and biological significance of the clear cells, we conducted histochemical staining (periodic acid-Schiff (PAS) with or without diastase digestion, alcian blue pH 2.5) and immunohistochemical staining (using antibodies against carcinoembryonic antigen (CEA), alpha-fetoprotein, p53 protein and Ki67 antigen) and also mitotic counts. Histologically, the changed area was characterized by pyknotic and randomly arranged nuclei with PAS-negative clear and vacuolated cytoplasm. Immunoreactivity for CEA was diffuse and strong in the clear cells, but not in the tumour cells in the ordinary portion of the adenomas. The Ki67 labelling index and the mitotic activity were both higher in the clear cell portion than in the ordinary portion.

This is the first study to indicate the incidence of clear cell change among colorectal adenomas. It has confirmed high proliferative activity within the clear cell portion of colorectal adenomas.