Colonoscopic findings and pathologic characteristics of Strongyloides colitis: a case series

Strongyloidiasis, which is caused by Strongyloides stercoralis, is one of the prevalent infections in the tropical and subtropical regions worldwide. The larvae mainly infect the small intestine and cause serious disseminated strongyloidiasis. Although upper gastrointestinal features in strongyloidiasis are well known, colonoscopic evaluation has not been established yet. The aim of this study is to clarify the characteristic findings on colonic lesions in strongyloidiasis.

From January 2005 to December 2009, 10 cases with strongyloidiasis underwent colonoscopy at a single center on an endemic island of Japan. The clinical and colonoscopic findings were analyzed retrospectively.

Six (60%) cases had an immunocompromised condition, including human T lymphotropic virus type 1 infection, corticosteroids, and chemotherapy. Hyperinfection or disseminated strongyloidiasis was not presented. Endoscopic features included yellowish-white nodules, erythema, and loss of vascular pattern, which were mainly observed in the right colon. Pathological examination revealed the filariform Strongyloides larvae and the eosinophilic infiltration of the lamina propria.

This study demonstrates that colonoscopic observation and biopsies are very useful to diagnose strongyloidiasis. Asymptomatic cases with strongyloidiasis can have colonic involvement. Yellowish-white nodules may be a characteristic finding of colonic lesions in strongyloidiasis and can be a cautious marker to prevent fatal disseminated strongyloidiasis in endemic regions.