title: Cap polyposis: a rare cause of rectal bleeding in children.
abstract: OBJECTIVE
  To evaluate the clinicopathological features and treatment outcomes of cap polyposis in the pediatric population.
  
  
  METHODS
  All pediatric patients with histologically proven diagnosis of cap polyposis were identified from our endoscopy and histology database over a 12 year period from 2000-2012 at our tertiary pediatric center, KK Women's and Children's Hospital in Singapore. The case records of these patients were retrospectively reviewed. The demographics, clinical course, laboratory results, endoscopic and histopathological features, treatments, and outcomes were analyzed. The study protocol was approved by the hospital institutional review board. The histological slides were reviewed by a pediatric histopathologist to confirm the diagnosis of cap polyposis.
  
  
  RESULTS
  Eleven patients were diagnosed with cap polyposis. The median patient age was 13 years (range 5-17 years); the sample included 7 males and 4 females. All of the patients presented with bloody stools. Seven patients (63%) had constipation, while 4 patients (36%) had diarrhea. All of the patients underwent colonoscopy and polypectomies (excluding 1 patient who refused polypectomy). The macroscopic findings were of polypoid lesions covered by fibrinopurulent exudates with normal intervening mucosa. The rectum was the most common involvement site (n = 9, 82%), followed by the rectosigmoid colon (n = 3, 18%). Five (45%) patients had fewer than 5 polyps, and 6 patients (65%) had multiple polyps. Histological examination of these polyps showed surface ulcerations with a cap of fibrin inflammatory exudate. Four (80%) patients with fewer than 5 polyps had complete resolution of symptoms following the polypectomy. One patient who did not consent to the polypectomy had resolution of symptoms after being treated with sulphasalazine. All 6 patients with multiple polyps experienced recurrence of bloody stools on follow-up (mean = 28 mo).
  
  
  CONCLUSIONS
  Cap polyposis is a rare and under-recognised cause of rectal bleeding in children. Our study has characterized the disease phenotype and treatment outcomes in a pediatric cohort.
authors.affiliation: Gastroenterology Service, Department of Pediatric Medicine, KK Women's and Children's Hospital, Singapore 229899, Singapore.
authors.forename: Jia Hui
authors.initials: JH
authors.lastname: Li
authors.forename: May Ying
authors.initials: MY
authors.lastname: Leong
authors.forename: Kong Boo
authors.initials: KB
authors.lastname: Phua
authors.forename: Yee
authors.initials: Y
authors.lastname: Low
authors.forename: Ajmal
authors.initials: A
authors.lastname: Kader
authors.forename: Veena
authors.initials: V
authors.lastname: Logarajah
authors.forename: Lin Yin
authors.initials: LY
authors.lastname: Ong
authors.forename: Joyce Hy
authors.initials: JH
authors.lastname: Chua
authors.forename: Christina
authors.initials: C
authors.lastname: Ong
mesh_terms: D000293:Adolescent; D000367:Age Factors; D002648:Child; D002675:Child, Preschool; D003111:Colonic Polyps / Q000150:complications* / Q000473:pathology / Q000628:therapy; D003113:Colonoscopy; D013505:Digestive System Surgical Procedures; D005260:Female; D005765:Gastrointestinal Agents / Q000627:therapeutic use; D006471:Gastrointestinal Hemorrhage / Q000209:etiology* / Q000473:pathology / Q000628:therapy; D006801:Humans; D008297:Male; D011127:Polyps / Q000150:complications* / Q000473:pathology / Q000628:therapy; D012002:Rectal Diseases / Q000150:complications* / Q000473:pathology / Q000628:therapy; D012008:Recurrence; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D005765:Gastrointestinal Agents
keywords: Cap polyposis; Inflammatory bowel disease; Pediatrics; Polyps; Rectal bleeding