A Comprehensive Review of Infectious Granulomatous Diseases of the Gastrointestinal Tract

Table 1

Comparison of imaging and microscopic findings together with regions of the gastrointestinal tract affected by bacterial causes of granulomatous disease.

Bacterial granulomatous etiologies	Location in the gastrointestinal tract	Imaging findings	Histological findings
Mycobacterium tuberculosis	Ileocecum → ascending colon → jejunum → appendix → duodenum → stomach → esophagus → sigmoid colon → rectum	Endoscopy; (i) 3 main types: ulcerative, hypertrophic, and ulcerohypertrophic; (ii) pseudopolyps, nodules, transverse ulcers, and a deformed ileocecal valve may be present; CT/MRI; (i) Concentric wall thickening, agape ileocecal valve, and strictures with prestenotic dilation	(i) Table 4 provides a detailed comparison of the histopathological features of M. tuberculosis and Crohn’s disease; Briefly; (i) Multiple, large granulomas per high power field; (ii) Caseating granulomas, with confluence, prominent lymphoid cuff, and architectural distortion; (iii) Epithelioid histiocyte ulcers, submucosal granulomas, lymphocyte cuffing, and excessive submucosal inflammation; (iv) AFB+
Bartonella henselae	Cat scratch disease; (i) Terminal ileum and colon; Bacillary angiomatosis; (i) Esophagus, stomach, duodenum, and colon	Endoscopy; (i) Multiple small ulcers throughout the GI tract in bacillary angiomatosis; CT abdomen; (i) Lymphadenitis (may present as protruding mass) and hypodense lesions in the liver and spleen	(i) Caseating granulomas with monoclonal B-cell clusters and microabscesses; (ii) In Bacillary angiomatosis, this finding together with the growth of bacteria in between collagen fibers or cluster around blood vessels; (iii) Warthin-Starry stain+
Yersinia bacterium	Terminal ileum, cecum, appendix, and mesenteric lymph nodes	Endoscopy; (i) Acute inflammation with purulent and necrotic lymphadenopathy in distal ileum and cecum; CT abdomen; (i) Evidence of pseudotumor, colitis, ulceration, and aphthoid ulcers in the region of the terminal ileum with or without mesenteric lymphadenopathy and appendiceal inflammation	(i) Numerous, large, suppurative epithelioid granulomas without evidence of monoclonal B cells with microabscesses; (ii) Y. pseudotuberculosis in later stages may present with neutrophilic invasion and scattered microabscesses with pus surrounded by a suppurative granuloma; (iii) Histology similar to Crohn’s disease may be present: transmural inflammation and cryptitis
Lymphogranuloma venereum	Rectum and distal colon	Endoscopy; (i) Like IBD, it will show chronic inflammatory changes with strictures and ulcerative lesions in the mucosa covered with pus, blood, and granulation tissue; CT abdomen; (i) Similar to IBD and will demonstrate fibrotic tissue, strictures, and fistulas in the colorectal region	(i) Acute inflammation stage may show cryptitis and crypt abscesses with minimal crypt distortion; (ii) The chronic inflammatory phase will show nonsuppurative epithelioid granulomatous inflammation with focal necrosis, numerous crypt abscesses, and without evidence of monoclonal B cells
Syphilis	Most commonly targets anus and rectum; stomach occasionally involved	Endoscopy; (i) Findings can range from proctitis to ulcers (numerous and irregular) and pseudotumors; (ii) In the early stages, a papule can be present within the mucosa of the anus/rectum and can later evolve into an ulcer resembling a typical chancre of primary syphilis	(i) Dense mononuclear cells with prominent plasma cells along with evidence of cryptitis, crypt abscess, and glandular destruction; (ii) Proliferative endarterteriologitis can be present; (iii) Syphilis is occasionally associated with caseating granulomas
Salmonellosis	Ileum, cecum, appendix, and right colon	Endoscopy; (i) Hyperemic mucosal patches with punched out mucosal ulcerations of various sizes and shapes (long, oval, or linear); (ii) Deep ulcers can reach the muscularis layer with risk of bleeding and perforation	(i) Hallmark finding—ulceration overlying hyperplastic Peyer’s patches leading to ulcerated lymphoid follicles; (ii) Histiocytic-rich granulomas (rare) admixed with lymphocytes and plasma cells in addition to areas of central necrosis. These specimens are deficient of neutrophils; (iii) Marked architectural distortion and crypt abscesses; (iv) IBD, TB, and Yersiniosis must be ruled out first as Salmonellosis is a common masquerader