Sialomucins in the assessment of dysplasia and cancer‐risk patients with ulcerative colitis treated with colectomy and ileo‐rectal anastomosis

Abstract

The clinical notes and histology of 374 patients treated by colectomy and ileo-rectal anastomosis for ulcerative colitis were reviewed. Only those with definite diagnosis of ulcerative colitis and follow-up rectal biopsies were included (171 cases). Morphology and patterns of mucin secretion were investigated to assess whether abnormal mucin with predominance of sialomucins is a useful indicator of malignancy-risk. Carcinoma has developed in six patients and 'precancer' in seven. The results show coexistence of dysplasia and sialomucin even in the absence of inflammation in all but three biopsies; in contrast the presence of both dysplasia and normal mucin profile was found in less than 1%. A significant correlation was noted between an inflamed mucosa and the development of cancer or precancer, the presence of sialomucins and the appearance of dysplasia. Sialomucins showed a greater sensitivity in detecting cancer than dysplasia (75% versus 30%). However, dysplasia was notably more specific (94% compared with 50%), hence its greater predictive value as indicator of malignancy (50% as against 15% for a positive sialomucin result). Mucin stains on routine fixed paraffin-embedded tissue provide a simple screening method to sharpen the assessment of dysplasia and cancer-risk in patients with ulcerative colitis despite the limitations referred to above. The lack of definite evidence of dysplasia in four patients who developed malignancy without premalignant changes in the rectal biopsies emphasises the need for frequent multiple biopsies in patients with an ileo-rectal anastomosis for ulcerative colitis.

Comparison of Mucin Patterns in Colonic Pathologies by Histochemistry

“…In UC increased production of sialomucins, decreased sulphomucins and reduction or loss of O-acetylation are observed. These changes appear to be related to the degree of inflammation and are particularly marked in dysplastic epithelium in the absence of inflammation, most frequently in colitis patients at risk of cancer [12,13].…”

Abnormal Patterns of Mucin Secretion in Ileal Neobladder Mucosa: Evidence of Preneoplastic Lesion?

“…Filipe and Branfoot [8]called these areas of sialomucin predominance in the colonic mucosa adjacent to neoplastic lesions, ‘transitional epithelium’ and, as a matter of fact, a change in the pattern of mucin production at the resection margin of colorectal cancers is considered to be of poor prognostic significance [20]. However, an increase in sialomucins has been reported in over half the benign inflammatory diseases and is not specific for neoplasia [21]. …”

Colon carcinogenesis in inflammatory bowel disease

“…with an even greater excess in dysplastic lesions (17,18). According to some studies, sialomucin predominance in UC was not only increased in areas of dysplasia, but also occurred in uninflammed mucosa remote from dysplasia (19,20) and prior to the development of dysplasia or cancer (19)(20)(21). Other investigators, however, found little or no difference in HID-AB staining in nondysplastic biopsies of UC patients with dysplasia or cancer and those without neoplasia (18,22).…”