The role of mucosal biopsy in the diagnosis of chronic diarrhea: value of multiple biopsies when colonoscopic finding is normal or nonspecific

Abstract

Objectives: There are controversies about taking routine mucosal biopsy when the gross colonoscopic finding is normal. This study was conducted to determine the frequency of clinically important histological abnormalities, prospectively, in chronic diarrhea patients with grossly normal or nonspecific colonoscopic findings.

Methods: One hundred and eighteen patients suffering from nonbloody diarrhea with average frequency of more than two times a day for more than 4 weeks were included. Multiple biopsies (cecum, ascending colon, mid-transverse colon, descending colon, sigmoid colon and rectum) were taken during colonoscopic examinations and each biopsy specimen was reviewed by one pathologist after H&E and Masson-trichrome staining.

Results: Clinically significant abnormalities (2 collagenous colitis, 1 lymphocytic colitis, 1 eosinophilic enterocolitis, 1 ulcerative colitis and 4 melanosis coli) were observed in 9 patients (7.6%). Sixteen cases (13.6%) of borderline histological abnormalities were observed (8 cases of possible collagenous colitis and 8 cases showing some features of lymphocytic colitis). Ninety two cases (78.8%) showed nonspecific inflammation only.

Conclusion: Clinically important histological lesions can exist in significant percentage in spite of normal or nonspecific colonoscopic findings, which can justify routine mucosal biopsy in the evaluation of chronic diarrhea patients. The clinical significance of borderline histological abnormalities needs to be determined by careful follow-up studies.

Fig. 1.

Masson-trichrome staining of the biopsy specimen obtained from a patient diagnosed as collagenous colitis (X400). The thickened collagen band, which measured more than 10μm is stained in dark color.

Fig. 2.

H&E staining of the biopsy specimen obtained from a patient diagnosed as lymphocytic colitis (X400). Intraepithelial lymphocyte infiltration proportionated more than 20% of epithelial cell population in this case. Evidences of surface epithelial cell damage, such as epithelial flattening and detachment, were also present.

Fig. 3.

Summary of histological findings observed in chronic diarrhea patients showing normal or nonspecific colonoscopic findings.