A Rare Case of Neonatal-Onset Diarrhea Due to Congenital Tufting Enteropathy: Clinical, Histopathological, and Genetic Insights.

Background and Clinical Significance: Congenital tufting enteropathy (CTE), or autosomal recessive congenital diarrhea type 5 (DIAR5), is a rare intestinal epithelial disorder characterized by severe neonatal-onset watery diarrhea, failure to thrive, and intestinal failure. Most cases are caused by biallelic EPCAM variants. Case Presentation: A 53-day-old female infant presented with severe watery diarrhea and failure to thrive from the first days of life. She was born at term with a birth weight of 3.4 kg and had 10-20 watery stools daily. At admission, she was dehydrated, dystrophic, and below the third weight percentile. Diarrhea persisted despite an amino acid-based formula and cessation of enteral feeding. Duodenal biopsy showed disturbed villous-crypt architecture, variable lamina propria inflammation, absence of intraepithelial lymphocytosis, epithelial tufts, and regenerative epithelial changes, supporting CTE. Whole-exome sequencing identified compound heterozygous EPCAM variants: a maternally inherited likely pathogenic frameshift variant, c.687_688del, p.(Lys230Asnfs*23), and a paternally inherited missense variant, c.757G>A, p.(Asp253Asn), classified as a variant of uncertain significance. TPN was initiated for intestinal failure. Follow-up was complicated by catheter-related sepsis, cholelithiasis, and recurrent pancreatitis requiring laparoscopic cholecystectomy. She subsequently tolerated limited enteral feeding but did not achieve enteral autonomy and remained dependent on TPN, while maintaining normal growth with nutritional support. Conclusions: CTE should be considered in infants with severe neonatal-onset diarrhea. Histopathology combined with genetic testing is essential for diagnosis. Long-term TPN and multidisciplinary management are required.