title: CT evaluation of nasolacrimal relapse of nasopharyngeal carcinoma.
abstract: OBJECTIVE
  The aim of the current study was to elucidate the anatomy of the nasolacrimal apparatus using computed tomography (CT), and to investigate the CT findings suggestive of recurrent nasopharyngeal carcinoma (NPC) involving the nasolacrimal apparatus.
  
  
  METHODS
  CT images of five patients with clinical or radiological findings suggestive of recurrent NPC who presented with nasolacrimal involvement were reviewed. Involvement of the lacrimal fossa, nasolacrimal canal (NLC), and adjacent anatomic structures including orbit and sinonasal cavities were noted.
  
  
  RESULTS
  CT in all patients demonstrated findings of NLC invasion and ostiomeatal complex obliteration. Four of the five patients showed medial canthal mass or pre-septal thickening, ethmoid bulla opacification and inferior nasal meatal involvement.
  
  
  CONCLUSIONS
  Knowledge of the anatomy of the nasolacrimal apparatus using CT is critical for evaluating images for tumour recurrence at this site. NLC invasion, a medial canthal mass and pre-septal thickening are important primary indicators for potential involvement of the nasolacrimal apparatus by recurrent NPC. Secondary signs suggesting this distinct form of relapse are obliteration of ostiomeatal channel, ethmoid bulla opacification and inferior nasal meatus involvement.
authors.affiliation: Department of Diagnostic Imaging, National Cancer Centre, Singapore. chingsc@ha.org.hk
authors.forename: A S C
authors.initials: AS
authors.lastname: Ching
authors.forename: V F H
authors.initials: VF
authors.lastname: Chong
authors.forename: J B K
authors.initials: JB
authors.lastname: Khoo
mesh_terms: D005260:Female; D006801:Humans; D007765:Lacrimal Apparatus / Q000000981:diagnostic imaging* / Q000473:pathology; D007766:Lacrimal Apparatus Diseases / Q000000981:diagnostic imaging* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009301:Nasolacrimal Duct / Q000000981:diagnostic imaging / Q000473:pathology; D009303:Nasopharyngeal Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging* / Q000473:pathology; D011379:Prognosis; D014057:Tomography, X-Ray Computed