MELANOSIS COLI (SO-CALLED "BROWN BOWEL")

概要

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The incidences of deposition of brown pigments in the human large bowel were found in 145 cases (33.1%) out of 438 colonic materials-92 in 280 autopsies, 47 in 110 operations and 6 in 48 biopsies. The frequency is higher in female sex, urinary organs, colon, and lowerabdominal tumors. On light microscopic study, the pigments are similar to the lipofuscin in the various staining, but they are electron microscopically different from lipofuscin of the heart and the liver. Furthermore, the pigments differ from both melanine pigments which exist in the normal epidermis and the malignant melanoma, and haemosiderins which are found in the liver and the haemorrhage sites. The pigment granules are found in the phagocytes of the colonic tunica mucosa, those transform from autophagosomes to autolysosomes, and then these granules change into residual bodies. On the clinical and light microscopic observation, we consider that contents of digestive tract are absorbed from free surface of the colonic mucous epithelial cells, and then those are transmitted to the phagocytes in the tunica mucosa. However, our observation did not reveal these transfering processes. We suggest that it is the so-called "Brown bowel" for naked-eye characters, but the nature of the pigment has yet to be clarified.