Context: Nonspecific changes (nonspecific chronic inflammation) in patients with chronic diarrhea represent the commonest diagnosis in colorectal biopsy interpretation, but these changes are of little clinical significance.
Objective: To find, within this group, histologic and immunohistologic diagnostic criteria to predict the duration and resolution of diarrhea.
Design: Detailed clinical features and histologic findings were analyzed in a cohort of 47 patients with chronic diarrhea, with near-normal histology and no clear-cut known etiologic agent. Immunohistochemistry to mast cells (CD117) and Treg cells (FOXP3) was also assessed in 39 patients.
Results: Increased number of lymphoid follicles and aggregates, increased number of mast cells, and paucity of Treg were the statistically significant key findings (P = .003, P = .008, and P = .04, respectively). The duration of diarrhea was correlated with the number of large lymphoid follicles and aggregates (P = .001, r = .48), number of total lymphoid follicles and aggregates (P = .003, r = .43), density of lymphoid follicles and aggregates (P = .009, r = .38), and total lymphoid follicles and aggregates per biopsy (P = .004, r = .42) and the number of mast cells (P = .001, r = .52). The number of mast cells and Treg cells showed significant difference between resolved and unresolved cases (P = .001 and P = .01 respectively).
Conclusions: Lymphocytic follicles and aggregates colitis, previously regarded as of negligible diagnostic significance, allows the prediction of the behavior of chronic diarrhea in a subset of patients with nonspecific changes on colonic biopsy. The increased number of mast cells and paucity of Treg cells further helps to identify such unresolved cases.