Case Report

Brown Bowel Syndrome Is a Rare and Commonly Missed Disease: A Case Report and Literature Review

Table 1

The key features of BBS for differential diagnosis.

Brown bowel syndrome
(1) Normal mucosa detected by endoscopy and histology (if no overlapping disease)
(2) PAS-positive pigments in smooth muscle cells of the muscularis propria
(3) EM: osmophilic pigments

Infection (Whipple disease and mycobacterium)
(1) Traveling or close contacting history
(2) Abnormal endoscopic findings
(3) PAS-positive granules in macrophages in lamina propria
(4) IHC for microorganism
(5) Normal muscularis propria
(6) EM: bacteria

Melanosis coli or duodeni
(1) Usually no clinical symptoms
(2) History of usage of anthraquinone laxatives or renal disease
(3) Dark endoscopic mucosa
(4) PAS-positive granules in macrophages in lamina propria

Celiac disease
(1) Inflamed duodenum detected by an endoscopy: scalloping or flattening of duodenal folds, fissuring over the folds, and a mosaic pattern of mucosa of folds
(2) Destruction of mucosa by intraepithelial lymphocytes
(3) Positive serology: antitransglutaminase antibodies, antiendomysial antibodies, and antigliadin antibodies
(4) Response to gluten-free products

Inflammatory bowel disease
(1) Bloody diarrhea
(2) Abnormal endoscopic findings: inflammation, ulcer, and loss of vascularity
(3) Active and chronic inflammation in mucosa or granuloma and transmural inflammation (Crohn’s disease)
(4) No pigments seen