Abstract: Background - Intestinal fibrosis is a major complication in people with inflammatory bowel disease and has been directly correlated to severity of mucosal injury and inflammation. The correlation of mucosal fibrosis with clinical disease activity and underlying diagnosis in cats with chronic enteropathy has not been investigated.
Hypothesis - Mucosal fibrosis is correlated to disease severity in cats with chronic enteropathy.
Animals - Small intestinal biopsy specimens from 27 cats with chronic enteropathy (13 cats with lymphoplasmacytic enteritis (LPE) and 14 cats with low-grade intestinal T-cell lymphoma (LGITL).
Methods - The proportional area of fibrosis in the lamina propria (fractional fibrotic area) was quantified in Masson’s-Trichrome-stained slides in 3 distinct mucosal regions (villi, apical crypts, and basal crypts). Analysis was performed using the software ImageJ. Results were correlated to a modified clinical disease activity index and the disease status of either LPE or LGITL.
Results - Fractional fibrotic area in the villi was significantly negatively correlated with the modified disease activity index (p=0.005). Cats with LPE had higher fractional fibrotic areas (median 12.6%, range 6.3 – 35.4%) in the apical crypt area compared to cats with LGITL (median 2.3%, range 0.0 - 52.2%) (p=0.05).
Conclusion - Cats with higher clinical disease activity show lower degrees of fibrosis in villi, which may be related to higher cellular infiltrates as seen in LGITL. Cats with LPE have more fibrosis in the apical crypt area compared to cats with LGITL. No fractional fibrotic area cut-off reliably differentiating LPE from LGITL has been established.
