| [ Summary ] |
Recent advancies in colonoscopic examination revealed many superficial-type colorectal tumors including depressed type tumors (IIc) and laterally spreading tumors (LST). LSTs have been known to have a morphological features that their vertical growth are very slight compared with their horizontal growth and they are classified into two subtypes : granular (LST-G) and non-granular (LST-NG). Morphologically, LST-NG have no granule or nodule and some cases of LST-NG have shallow depression, LST-NG is similar to depressed type tumors.
We investigated the histopathological and molecularpathological features of LST-NG compared with depressed type colorectal tumors. Histopathologically, LST-NGs had the demarcation points made by tumor glands and non-tumor glands, and most of LST-NGs had straight tumor glands without budding growth similar to depressed type tumors. Molecularpathologically, LST-NG is similar to depressed type tumor in that LST-NGs showed few K-ras mutations and a third cases of the LST-NG showed p53-immunoreactivities diffusely, however, LST-NG is not similar to depressed type tumor in that most cases of LST-NGs preserved membranous expression of E-cadherin. Preserved membranous expression of E-cadherin may promote superficial spreading of tumor cells of LST. |