title: Emphasis on the MR imaging findings of brown tumor: a report of five cases.
abstract: OBJECTIVE
  Brown tumors are focal reactive osteolytic lesions that are encountered in patients with primary or secondary hyperparathyroidism, and these tumors have nonspecific magnetic resonance (MR) imaging findings. However, there are only a few reports on MR imaging of brown tumors. The purpose of this study is to describe the spectrum of MR imaging findings of brown tumors.
  
  
  METHODS
  The MR imaging features of five patients with clinical and pathological evidence of brown tumor were retrospectively reviewed by two radiologists. The patients had primary hyperparathyroidism, which was confirmed as parathyroid adenoma (n = 2) and parathyroid carcinoma (n = 3). The MR images were evaluated for the presence of solid or cystic portions, the signal intensity of the lesions, the contrast enhancement pattern and the presence of cortex destruction and fluid-fluid levels.
  
  
  RESULTS
  Twelve bone lesions were detected on the MR images of five patients; three lesions in two patients, four lesions in one patient, and one lesion in two patients. The tumor was solid in three lesions, mixed solid and cystic in four, and cystic in five. All the solid lesions were accompanied by mixed lesions. Discontinuity of the cortex and adjacent soft-tissue enhancement were seen in all the solid lesions. Fluid-fluid levels were seen in two cases within the cystic component of the mixed lesions and cystic lesions.
  
  
  CONCLUSIONS
  The five patients with brown tumor demonstrated a wide spectrum of MR imaging findings. There are few lesions that are osteolytic on the radiographs and that show a short T2 on MR imaging, such as brown tumor. Multiple cystic or mixed lesions are the expected findings of brown tumors.
authors.affiliation: Department of Radiology, The Catholic University of Korea, College of Medicine, Bucheon St. Mary's Hospital, Sosa-dong, Bucheon, Kyunggi-do, 420-717, Korea.
authors.forename: Won Sun
authors.initials: WS
authors.lastname: Hong
authors.forename: Mi Sook
authors.initials: MS
authors.lastname: Sung
authors.forename: Kyung-Ah
authors.initials: KA
authors.lastname: Chun
authors.forename: Jee-Young
authors.initials: JY
authors.lastname: Kim
authors.forename: Sun-Won
authors.initials: SW
authors.lastname: Park
authors.forename: Kee-Haeng
authors.initials: KH
authors.lastname: Lee
authors.forename: Hyun Wook
authors.initials: HW
authors.lastname: Lim
authors.forename: Yeon Soo
authors.initials: YS
authors.lastname: Lim
authors.forename: Won Jong
authors.initials: WJ
authors.lastname: Yoo
authors.forename: Myung Hee
authors.initials: MH
authors.lastname: Chung
mesh_terms: D000328:Adult; D001842:Bone and Bones / Q000473:pathology*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D006961:Hyperparathyroidism / Q000150:complications* / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010002:Osteitis Fibrosa Cystica / Q000209:etiology* / Q000473:pathology*