Supplementary Material for: Case Report – Pneumatosis Intestinalis in a Well-Appearing Preterm Infant: An Unusual Presentation of Protein-Induced Proctocolitis

Introduction. It is well known that food protein-induced allergic proctocolitis (FPIAP) usually presents with bloody stools in otherwise healthy infants, but there are only a few reports discussing its potential association with pneumatosis intestinalis. Case Presentation. A preterm infant, born at 33 weeks’ gestation, developed bloody stools while on full enteral feeds of breast milk and preterm formula. His physical examination was unremarkable. Abdominal radiographs revealed pneumatosis affecting the whole colon and rectum, prompting withholding of feeds and initiation of broad-spectrum antibiotics. The infant remained well-appearing at all times and did not develop laboratory abnormalities. Antibiotics were discontinued after 72 hours of treatment, and feeds were resumed with dairy-free mother’s milk supplemented with extensively hydrolyzed formula without further concerns. The clinical picture of this patient and his response to dietary modification are highly suggestive of FPIAP. Conclusion. Though pneumatosis is strongly associated with necrotizing enterocolitis, FPIAP should also be considered in infants who are well appearing, have a normal abdominal exam, and lack systemic signs of illness.