Which features distinguish strongyloidiasis from ulcerative colitis

 Q: 44 years old male, a recently migrant from southeast Asia is admitted to ICU with gastrointestinal (GI) symptoms including pain and lower GI bleed. Subsequent workup led to the presumed diagnosis of strongyloidiasis. Colonoscopy is performed to rule out ulcerative colitis. Which features distinguish strongyloidiasis from ulcerative colitis?

Answer: 

Strongyloides colitis can mimic ulcerative colitis. Although endoscopies are not routinely performed in strongyloidiasis but may require ruling out other potentially life-threatening conditions. Strongyloides colitis can be differentiated from ulcerative colitis by noticing skip pattern of inflammation, distal attenuation of the disease, eosinophil-rich infiltrates, relatively intact crypt architecture, and frequent involvement of submucosa with erythematous nodules. 

 

If upper endoscopy is performed, the stomach may show thickened folds and mucosal erosions. And, the duodenum may show edema, brown mucosal discoloration, erythematous spots, subepithelial hemorrhages, and megaduodenum. A biopsy can be taken to document parasites in the gastric crypts or duodenal glands and eosinophilic infiltration of the lamina propria.

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References:

1. Rivasi F, Pampiglione S, Boldorini R, Cardinale L. Histopathology of gastric and duodenal Strongyloides stercoralis locations in fifteen immunocompromised subjects. Arch Pathol Lab Med 2006; 130:1792. 

2. Overstreet K, Chen J, Rodriguez JW, Wiener G. Endoscopic and histopathologic findings of Strongyloides stercoralis infection in a patient with AIDS. Gastrointest Endosc 2003; 58:928.

3. Qu Z, Kundu UR, Abadeer RA, Wanger A. Strongyloides colitis is a lethal mimic of ulcerative colitis: the key morphologic differential diagnosis. Hum Pathol 2009; 40:572. 

4. Thompson BF, Fry LC, Wells CD, et al. The spectrum of GI strongyloidiasis: an endoscopic-pathologic study. Gastrointest Endosc 2004; 59:906.