Figure 3.74 Chronic inflammation, nonspecific. Not uncommonly, small bowel biopsies show a chronic inflammatory infiltrate without other specific features. Following systematic review of all tissue compartments for clues, and chart review for clinical correlates, some cases just remain “nonspecific.”
CHECKLIST: Etiologic Considerations for the Chronic Inflammation Pattern
Reactive Duodenopathy
Inflammatory Bowel Disease
Infection
Inflammatory or Immune-Regulated Disorders (i.e., Psoriasis)
The chronic inflammation pattern is defined by mild expansion of the lamina propria with mononuclear cells or lymphoid aggregates in the absence of villous blunting or intraepithelial lymphocytosis (Fig. 3.74). This is the most nonspecific of the small bowel patterns, but also among the most common. Etiologic considerations include reactive duodenopathy (see Malabsorption Pattern, this chapter), infection, and upper tract involvement by IBD (Figs. 3.75and 3.76). Up to 40% of patients with Crohn disease may show active, chronic, and granulomatous inflammation in varying proportions.14 By comparison, ulcerative colitis is typically limited to the lower gastrointestinal tract, although up to 10% of ulcerative colitis patients may demonstrate a diffuse chronic duodenitis.15 Keep in mind, however, that IBD is a primary consideration only when the changes are “focally enhanced” (Figs. 3.77 and 3.78) (See Focally Enhanced Gastritis, Stomach Chapter) or are accompanied by mucosal granulomata, or if lower gastrointestinal tract disease is present. Sampling error in the duodenum may result in the lack of specific features, and this can raise a host of other differential diagnoses, such as medication-induced changes, upstream gastric disease, and other inflammatory or immune-regulated disorders. One such example is psoriasis, which may show mild duodenal inflammation and mast cell infiltration.16–18 It is perhaps, therefore, best not to speculate on the etiology of a mild nonspecific duodenitis in the absence of clinical information. Rather, simple documentation of the mild abnormality and acknowledgement of pertinent negatives are sufficient.
Figure 3.75 Chronic inflammation, nonspecific, duodenal giardiasis. Chronic inflammation in the small bowel is often nonspecific, but routine careful examination of all the tissue compartments may yield diagnostic findings. This example shows a prominent lymphoid aggregate and some dilated lacteals (arrow) in this duodenal biopsy. The tissue findings are nonspecific, but the diagnosis resides in the space between the villi (arrowhead).
Figure 3.76 Chronic inflammation, nonspecific, duodenal giardiasis Higher magnification of the indicated area in the previous figure reveals the protozoa Giardia.
Figure 3.77 Chronic inflammation, focally enhanced, duodenal Crohn disease. This biopsy shows a pattern of focally enhanced inflammation in a patient with duodenal Crohn disease. The findings are nonspecific and consist of localized inflammation, which should be interpreted in the proper clinical setting.
Figure 3.78 Chronic inflammation, nonspecific, duodenal Crohn disease. Higher magnification of the previous figure shows cryptitis (arrowheads) consistent with the patient’s known history of duodenal involvement by Crohn disease.
SAMPLE NOTE: SMALL BOWEL WITH MILD CHRONIC INFLAMMATION, BUT NO OTHER SPECIFIC FEATURES:
Small Bowel, Biopsy:
• Small intestinal mucosa with mildly increased lamina propria chronic inflammation, nonspecific.
• Negative for intraepithelial lymphocytosis or villous blunting.