title: Paediatric parotid neoplasms: a 10 year retrospective imaging and pathology review of these rare tumours.
abstract: OBJECTIVE
  To determine the relative incidence of benign and malignant paediatric parotid gland tumours and whether particular presenting symptoms or imaging characteristics were more likely to predict malignancy.
  
  
  METHODS
  Hospital records were reviewed for all patients <18 years with histopathology-proven parotid neoplasms over the 10 year period from 2003-2013. Infantile haemangiomas and patients with neurofibromatosis type I were excluded. The presenting clinical symptoms for each patient were recorded. All available CT and MRI examinations for these patients were evaluated for tumour imaging characteristics.
  
  
  RESULTS
  Seventeen patients (nine boys, eight girls; age range 2-17 years) were identified with neoplastic parotid masses; 11 tumours were malignant (65%) and six were benign (35%). The malignant tumours consisted of three acinic cell carcinomas, two mucoepidermoid carcinomas, one alveolar rhabdomyosarcoma, one poorly differentiated carcinoma, one low-grade adenocarcinoma, and three metastases (two melanoma, one orbital medulloepithelioma). The benign tumours consisted of five pleomorphic adenomas and one schwannoma. Presenting clinical symptoms were similar between benign and malignant tumours. Twelve MRI and six CT examinations were available for review with five patients undergoing both techniques. MRI features commonly identified with malignant tumours included: hypointense T2 signal, restricted diffusion, ill-defined borders, and focal necrosis. Only four of the six tumours imaged at CT were visualized, and of those, the margins were indeterminate in three patients.
  
  
  CONCLUSIONS
  Paediatric parotid masses are more likely to be malignant than benign. Presenting clinical symptoms and CT are not helpful for distinguishing benign and malignant disease. MRI features such as T2 hypointensity, restricted diffusion, ill-defined borders, and focal necrosis, although not specific, should raise concern for malignancy.
authors.affiliation: Department of Radiology and Biomedical Imaging University of California, San Francisco, 505 Parnassus Ave, L358, San Francisco, CA 94143, USA. Electronic address: mark.mamlouk@ucsf.edu.
authors.forename: M D
authors.initials: MD
authors.lastname: Mamlouk
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery University of California, San Francisco, 2330 Post Street, Suite 310, San Francisco, CA 94115, USA.
authors.forename: K W
authors.initials: KW
authors.lastname: Rosbe
authors.affiliation: Department of Radiology and Biomedical Imaging University of California, San Francisco, 505 Parnassus Ave, L358, San Francisco, CA 94143, USA; Department of Otolaryngology-Head and Neck Surgery University of California, San Francisco, 2330 Post Street, Suite 310, San Francisco, CA 94115, USA.
authors.forename: C M
authors.initials: CM
authors.lastname: Glastonbury
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D010306:Parotid Gland / Q000000981:diagnostic imaging / Q000473:pathology; D010307:Parotid Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology*; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*