Mucin histochemistry--a simple and effective method for diagnosing premalignant and early malignant lesions of lower gastrointestinal tract.

Mucin histochemistry of colo-rectal mucosa was studied in 124 biopsies which included 28 specimens from normal mucosa, 35 inflammatory lesions, 20 polyps, 26 malignant lesions and 15 specimens from transitional mucosa. The stains used were Haematoxylin and Eosin, Periodic acid schiffs, Alcian blue--Periodic acid schiffs (pH 2.5), Orcein--Alcian blue and Periodic acid sodium borohydride saponification. Normal mucosa, mucosa from inflammatory lesions, juvenile and hyperplastic polyps had neutral mucin in traces along with O-acylated sialomucins and sulphomucins. Predominant changes in adenomatous polyps and malignancy were a significant loss of sulphomucins and O-acylation at position C7, C8 or C9 in sialomucins. The changes in transitional mucosa were more on the pattern of malignant lesions. The alterations in the amount and/or pattern of mucin in colorectal mucosa has been found to predate frank morphological changes of malignancy. A routine use of mucin histochemistry in suspicious colorectal biopsies might be helpful in diagnosing premalignant and early malignant lesions in otherwise apparently normal colorectal mucosa or mucosa with chronic inflammatory changes and thereby reduce mortality.