Which histological finding might indicate factitious diarrhea upon colonoscopy?

The presence of brown discoloration of the colon with pigment macrophages in the lamina propria is a significant histological finding that may indicate factitious diarrhea. This condition can occur when individuals self-administer laxatives or other substances to induce diarrhea, which can lead to a particular desquamation of the colon and accumulation of pigment. The pigment macrophages reflect the body's response to the laxative use, often seen as a result of hematopoiesis in response to the absorbed laxatives, resulting in the characteristic brown discoloration. This specific finding serves as a marker for the use of substances that alter normal bowel function and distinctively points towards factitious diarrhea rather than organic causes of colonic disease.

In contrast, the other options represent findings more typical of underlying organic diseases. Crypt abscesses are associated with conditions like ulcerative colitis or Crohn's disease, inflammatory polyps can indicate chronic inflammation, and granulomas are often seen in Crohn’s disease and other granulomatous diseases. Each of these findings points to a pathological process rather than a behavioral condition like factitious diarrhea. Identifying the brown discoloration with pigment macrophages is key to recognizing and differentiating factitious diarrhea from other gastrointestinal disorders.