title: Outcome of infants presenting rectal bleeding: a retrospective study in a single institution.
abstract: BACKGROUND
  Although rectal bleeding in infancy (RBI) is not a rare phenomenon, the clinical course of RBI is not fully understood.
  
  
  METHODS
  To investigate the outcome and pathogenesis of RBI, especially when concomitant with food-protein-induced proctocolitis (FPIP) and neonatal transient eosinophilic colitis (NTEC), 22 neonates with rectal bleeding with FPIP and NTEC from January 2008 to June 2012 were enrolled and their clinical course and mechanisms of inflammation were examined.
  
  
  RESULTS
  Thirteen infants showed rectal bleeding after feeding and were diagnosed with FPIP, and nine infants showed rectal bleeding before feeding and were diagnosed with NTEC. Elevated peripheral white blood cell (12,685 ± 3754/μl and 30,978 ± 16,166/μl) and eosinophil (1084 ± 816/μl and 4456 ± 3341/μl) were confirmed in FPIP and NTEC, respectively. Colonoscopy revealed nodular lymphoid hyperplasia, a pale mucosal surface and oozing with diffuse infiltration of neutrophils, lymphocytes, and eosinophils in both groups. Reverse transcription polymerase chain reaction analysis revealed enhanced expression of the interleukin-6, CCL11, and CXCL13 genes, where CXCL13 expression was more prominent in FPIP. Mucosal infiltration by CD3- and immunoglobulin-A- but not immunoglobulin-E-positive cells was confirmed. Among them, only one infant with FPIP developed milk allergy, whereas none with NTEC had developed milk allergy at the age of 1 year.
  
  
  CONCLUSIONS
  FPIP in infancy and NTEC are similar diseases and interleukin-6, CCL11, and CXCL13 may play a major role in the pathogenesis of rectal bleeding. Although the involvement of allergic reaction is possible, milk allergy was not a common outcome after 1 year of follow up.
authors.affiliation: Department of Pediatrics and Adolescent Medicine, Juntendo University Graduate School of Medicine, Tokyo, Japan.
authors.forename: Mari
authors.initials: M
authors.lastname: Mori
authors.affiliation: Department of Pediatrics and Adolescent Medicine, Juntendo University Graduate School of Medicine, Tokyo, Japan.
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Ohtsuka
authors.affiliation: Department of Pediatrics and Adolescent Medicine, Juntendo University Graduate School of Medicine, Tokyo, Japan.
authors.forename: Asuka
authors.initials: A
authors.lastname: Ishida
authors.affiliation: Department of Pediatrics and Adolescent Medicine, Juntendo University Graduate School of Medicine, Tokyo, Japan.
authors.forename: Susumu
authors.initials: S
authors.lastname: Yamazaki
authors.affiliation: Department of Pediatrics and Adolescent Medicine, Juntendo University Graduate School of Medicine, Tokyo, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Jimbo
authors.affiliation: Department of Pediatrics and Adolescent Medicine, Juntendo University Graduate School of Medicine, Tokyo, Japan.
authors.forename: Eisuke
authors.initials: E
authors.lastname: Inage
authors.affiliation: Department of Pediatrics and Adolescent Medicine, Juntendo University Graduate School of Medicine, Tokyo, Japan.
authors.forename: Yo
authors.initials: Y
authors.lastname: Aoyagi
authors.affiliation: Department of Pediatrics and Adolescent Medicine, Juntendo University Graduate School of Medicine, Tokyo, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Kudo
authors.affiliation: Department of Pediatrics and Adolescent Medicine, Juntendo University Graduate School of Medicine, Tokyo, Japan.
authors.forename: Ryuyo
authors.initials: R
authors.lastname: Suzuki
authors.affiliation: Department of Pediatrics and Adolescent Medicine, Juntendo University Graduate School of Medicine, Tokyo, Japan.
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Shimizu
mesh_terms: D054413:Chemokine CCL11 / Q000097:blood; D004802:Eosinophilia / Q000097:blood / Q000150:complications / Q000175:diagnosis*; D005260:Female; D006471:Gastrointestinal Hemorrhage / Q000097:blood / Q000175:diagnosis* / Q000209:etiology*; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D018945:Monocyte Chemoattractant Proteins / Q000097:blood; D011350:Proctocolitis / Q000097:blood / Q000150:complications / Q000175:diagnosis*; D012189:Retrospective Studies
chemical_list: C515456:CCL11 protein, human; C099677:CCL13 protein, human; D054413:Chemokine CCL11; D018945:Monocyte Chemoattractant Proteins
keywords: food-protein-induced proctocolitis; lymphoid hyperplasia; neonatal transient eosinophilic colitis; non-immunoglobulin-E-mediated allergic reaction; rectal bleeding in infancy