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Microscopic colitis as a missed cause of chronic diarrhea
Nooroudien Mohamed1, Monique Marais, Juanita Bezuidenhout
1Department of Pathology, Division of Anatomical Pathology, Faculty of Health Sciences, University of Stellenbosch, National Health Laboratory Services, Tygerberg Academic Hospital, Tygerberg 7505, South Africa. noor@sun.ac.za
Insights
Increased intraepithelial lymphocytes (IELs) are found in 8.3% of patients with normal colonoscopies. Immunohistochemistry aids in diagnosing microscopic colitis, especially in those with irritable bowel syndrome.
Area of Science:
- Gastroenterology
- Histopathology
- Immunohistochemistry
Background:
- Microscopic colitis is often diagnosed late.
- Increased intraepithelial lymphocytes (IELs) may indicate microscopic colitis.
- Standard colonoscopy may miss subtle findings.
Purpose of the Study:
- To determine the prevalence of increased IELs in patients with normal colonoscopies.
- To evaluate the utility of immunohistochemistry in identifying microscopic colitis.
- To assess the diagnostic yield of CD3 staining for IELs.
Main Methods:
- Retrospective review of 241 non-malignant colon biopsies.
- Immunohistochemistry using CD3 to count IELs.
- Correlation of IEL counts (≥ 20 IELs/100 cells) with clinical data.
Main Results:
- 8.3% of patients (20/241) had increased IELs (≥ 20).
- Lymphocytic colitis was identified in 2.5% (6/241), with 5/6 missed on initial evaluation.
- Increased IELs were associated with diarrhea-predominant IBS, abdominal pain, constipation, and weight loss.
Conclusions:
- Immunohistochemistry with CD3 is valuable for quantifying IELs.
- This method aids in diagnosing microscopic colitis in patients with normal-appearing biopsies.
- CD3 immunohistochemistry is particularly useful for identifying microscopic colitis in patients with diarrhea-predominant IBS.
Aim:
To determine the prevalence of increased intraepithelial lymphocytes, using immunohistochemistry in patients with normal colonoscopy and near normal biopsy.
Methods:
We retrospectively reviewed all non-malignant colon mucosal biopsies between 2005 and 2007, reported as normal, chronic inflammation or melanosis coli in patients who were undergoing routine colonoscopy. Immunohistochemistry using CD3 was performed on all mucosal biopsies and an intraepithelial lymphocyte count (IEL) was determined. Cases with an IEL count of ≥ 20 IELs per 100 surface epithelial cells were correlated with demographic, clinical and follow-up data. A further subgroup was evaluated for lymphocytic colitis.
Results:
Twenty (8.3%) of 241 cases revealed an IEL count ≥ 20. Six (2.5%) patients were identified as having lymphocytic colitis (P < 0.001), of whom, five were missed on initial evaluation (P = 0.01). Four of these five patients were labeled with diarrhea-predominant irritable bowel syndrome (IBS). On follow-up, three of the remaining 20 cases were diagnosed with malignancy (renal cell carcinoma and myelodysplastic syndrome) and one had an unknown primary tumor with multiple liver metastases. Two cases of collagenous colitis with an IEL count < 10 were included in this study. Increased IELs were not confined to patients with diarrhea as a primary presenting symptom, but were also present in patients with abdominal pain (n = 7), constipation (n = 3) and loss of weight (n = 1).
Conclusion:
Immunohistochemistry using CD3 is of value in identifying and quantifying IELs for the presence of microscopic colitis in patients with diarrhea-predominant IBS.
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