Case Report: Congenital chloride diarrhea in a prepubertal girl with perianal fistula and colonic ulcers.

Congenital chloride diarrhea (CCD) is a rare genetic disorder characterized by persistent watery diarrhea and electrolyte imbalances. Herein, we report the case of a 6-year-old girl with a significantly delayed diagnosis of CCD, who had been misdiagnosed with Bartter syndrome since infancy due to atypical symptoms. Notably, the patient presented with rare gastrointestinal complications, including colonic ulcerations and an active perianal fistula. While the colonic ulcerations resolved under standard conservative medical treatment, the concurrent perianal fistula completely healed using an innovative, non-surgical approach consisting of local rectal antibiotic application (cefdinir powder) and antiseptic sitz baths. This case demonstrates that CCD can present with unusual structural complications. Crucially, although CCD typically manifests in early infancy, clinicians should consider this genetic metabolic disorder even in older children presenting with chronic diarrhea and recurrent electrolyte disturbances.