The first report on effect of fecal microbiota transplantation as a complementary treatment in a patient with steroid-refractory Cronkhite-Canada syndrome: A case report.

Rationale: Cronkhite-Canada syndrome (CCS) is a rare non-hereditary disease of unknown etiology that is characterized by the appearance of multiple polyps in the entire gastrointestinal (GI) tract, except in the esophagus, with GI and non-GI symptoms. Various factors are associated with the pathogenesis of CCS. Immune dysregulation has been discussed as one of the pathogeneses of CCS, and dysbiosis of the gut microbiota can affect the immune system. Currently, standard treatment has not been established.

Patient Concerns And Diagnosis: We present the treatment with fecal microbiota transplantation (FMT) in a 67-year-old male patient with steroid-refractory CCS who could not undergo anti-tumor necrosis factor-a treatment due to suspected tuberculosis infection.

Interventions: FMT has recently attracted attention as a method of overcoming drug resistance through immunomodulatory effects through microbiome regulation. We collected the patient's stool samples before FMT and 8weeks after FMT.

Outcomes: We analyzed the microbiome composition of patients by sequencing the V3-V4 region of the 16s rRNA gene (Miseq). After FMT, the number of episodes of diarrhea and hypoalbuminemia were also corrected. The Chao 1 index after FMT, which was significantly higher than that of donors before FMT, changed to a similar level for donors after FMT. Fusobacterium nucleatum, Pyramidobacter piscolens, and Campylobacter concisus disappeared after FMT, suggesting the presence of an association between gut microbiota and CCS.

Lessons: Furthermore, we provide the possibility that microbiome modulation by FMT could serve as a complementary treatment in patients with steroid-refractory CCS.