title: CT and MRI features of recurrent tumors and second primary neoplasms in pediatric patients with retinoblastoma.
abstract: OBJECTIVE
  The aim of our study was to describe the CT and MRI findings of recurrent tumors and second primary (malignant and benign) neoplasms in patients with retinoblastoma and to evaluate imaging features to assist in distinguishing them.
  
  
  METHODS
  Records of 445 pathologically confirmed retinoblastomas were retrospectively reviewed. Thirty-four patients with recurrent retinoblastomas and 15 patients with second primary neoplasms who underwent CT and MRI were evaluated by two radiologists with agreement by consensus.
  
  
  RESULTS
  Invasive patterns of recurrent tumors included type A, intraocular tumor (n = 13); type B, intraorbital tumor with spread into the optic nerve shown as enlargement and marked enhancement of the optic nerve on contrast-enhanced CT or MRI (n = 6); and type C, tumor extending to the lateral aspect of the orbit and invading the brain via the sphenoidal bone (n = 2). Thirty-eight percent of patients with recurrent tumors had distant metastases (n = 7) or leptomeningeal metastases (n = 6). Leptomeningeal metastases were found only in recurrent tumors. Second primary neoplasms included osteosarcoma (n = 5), rhabdomyosarcoma (n = 5), meningioma (n = 4), and other tumors (n = 3). A significant difference was seen between the patients' ages at the time of diagnosis of recurrent tumors and second primary neoplasms (p < 0.0001). Extraorbital tumors were found more frequently among second primary neoplasms than among recurrent tumors (p < 0.001).
  
  
  CONCLUSIONS
  Both recurrent tumors and second primary neoplasms in patients with retinoblastoma often show characteristic imaging features. The tumor distribution on CT and MRI may help in differentiating recurrent tumors and second primary neoplasms.
authors.affiliation: Division of Diagnostic Radiology, National Cancer Center Hospital and Research Institute, 5-1-1, Tsukiji, Chuo-Ku, 104-0045 Tokyo, Japan.
authors.forename: Ukihide
authors.initials: U
authors.lastname: Tateishi
authors.forename: Tadashi
authors.initials: T
authors.lastname: Hasegawa
authors.forename: Kunihisa
authors.initials: K
authors.lastname: Miyakawa
authors.forename: Minako
authors.initials: M
authors.lastname: Sumi
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Moriyama
mesh_terms: D000293:Adolescent; D000367:Age Factors; D002648:Child; D002675:Child, Preschool; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007223:Infant; D008279:Magnetic Resonance Imaging; D008297:Male; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging* / Q000473:pathology*; D016609:Neoplasms, Second Primary / Q000000981:diagnostic imaging* / Q000473:pathology*; D015203:Reproducibility of Results; D019572:Retinal Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology*; D012175:Retinoblastoma / Q000000981:diagnostic imaging* / Q000473:pathology*; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed