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

Aims: The aim of our investigation was to clarify the histological characte ristics and biological significance of clear cell change in colorectal aden omas. Methods and results: We found three cases (0.086%) of tubular adenomas with clear cell change in a review of 3486 cases of colorectal adenoma. These t hree cases occurred in male patients and were located in the left-sided col on. To investigate the nature and biological significance of the clear cell s, we conducted histochemical staining (periodic acid-Schiff (PAS) with or without diastase digestion, alcian blue pH 2.5) and immunohistochemical sta ining (using antibodies against carcinoembryonic antigen (CEA), alpha-fetop rotein, p53 protein and Ki67 antigen)and also mitotic counts. Histologicall y, the changed area was characterized by pyknotic and randomly arranged nuc lei 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 m itotic activity were both higher in the clear cell portion than in the ordi nary portion, Conclusions: This is the first studs to indicate the incidence of clear cel l change among colorectal incidence of clear cell change among colorectal a denomas. It has confirmed high proliferative activity within the clear cell port-ion of colorectal adenomas.