title: Rebound adenoid hyperplasia after chemotherapy in pediatric patients with head and neck lymphoma: MR imaging findings.
abstract: OBJECTIVE
  To assess MR imaging findings of rebound adenoid hyperplasia after chemotherapy in pediatric patients with head and neck lymphoma.
  
  
  METHODS
  Eight pediatric patients with head and neck lymphoma treated with chemotherapy alone or concurrent chemoradiotherapy were included. All patients underwent pre-therapeutic assessment and post-therapeutic follow-up by MR imaging. The maximum thickness of the adenoid was assessed on transverse T2-weighted images. Rebound adenoid hyperplasia was defined as more than half of the pre-therapeutic thickness after severe atrophy.
  
  
  RESULTS
  The pre-therapeutic maximum thickness of the adenoid ranged from 10 to 18 mm (mean, 15 mm). In all patients, the thickness of the adenoid dramatically decreased (mean 1 mm) within 1 year after the cessation of chemotherapy. On follow-up MR imaging, rebound adenoid hyperplasia was observed in five patients (63 %). Re-atrophy following rebound adenoid hyperplasia was observed in two patients (25 %), and no re-atrophy was observed in three patients (37 %). Rebound adenoid hyperplasia was not observed in three patients (37 %) who were in their late teens, and who had been treated with concurrent chemoradiotherapy.
  
  
  CONCLUSIONS
  Rebound adenoid hyperplasia was often observed after chemotherapy in pediatric patients with lymphoma. MR imaging was useful for the assessment of rebound adenoid hyperplasia.
authors.affiliation: Department of Radiology, Gifu University School of Medicine, 1-1 Yanagido, Gifu, 501-1194, Japan. hkato@gifu-u.ac.jp.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Kato
authors.affiliation: Department of Radiology, Gifu University School of Medicine, 1-1 Yanagido, Gifu, 501-1194, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Matsuo
authors.affiliation: Department of Pediatrics, Gifu University School of Medicine, Gifu, Japan.
authors.forename: Michio
authors.initials: M
authors.lastname: Ozeki
authors.affiliation: Department of Pediatrics, Gifu University School of Medicine, Gifu, Japan.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Fukao
mesh_terms: D000234:Adenoids / Q000000981:diagnostic imaging* / Q000473:pathology*; D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D006258:Head and Neck Neoplasms / Q000188:drug therapy*; D006801:Humans; D006965:Hyperplasia; D008223:Lymphoma / Q000188:drug therapy*; D008279:Magnetic Resonance Imaging; D008297:Male; D055815:Young Adult
keywords: Chemotherapy; Child; Lymphoma; MR imaging; Rebound adenoid hyperplasia