title: Computed tomography and magnetic resonance imaging findings of intraorbital granular cell tumor (Abrikossoff's tumor): a case report.
abstract: BACKGROUND
  Granular cell tumors are rare neoplasms which can occur in any part of the body. Granular cell tumors of the orbit account for only 3 % of all granular cell tumor cases. Computed tomography and magnetic resonance imaging of the orbit have proven useful for diagnosing orbital tumors. However, the rarity of intraorbital granular cell tumors poses a significant diagnostic challenge for both clinicians and radiologists.
  
  
  METHODS
  We report a case of a 37-year-old Chinese woman with a rare intraocular granular cell tumor of her right eye presenting with diplopia, proptosis, and restriction of ocular movement. Preoperative orbital computed tomography and magnetic resonance imaging with contrast enhancement revealed an enhancing solid, ovoid, well-demarcated, retrobulbar nodule. In addition, magnetic resonance imaging features included an intraorbital tumor which was isointense relative to gray matter on T1-weighted imaging and hypointense on T2-weighted imaging. No diffusion restriction of water was noted on either axial diffusion-weighted images or apparent diffusion coefficient maps. Both computed tomography and magnetic resonance imaging features suggested an intraorbital hemangioma. However, postoperative pathology (together with immunohistochemistry) identified an intraorbital granular cell tumor.
  
  
  CONCLUSIONS
  When intraorbital T2 hypointensity and free diffusion of water are observed on magnetic resonance imaging, a granular cell tumor should be included in the differential diagnosis of an intraocular tumor.
authors.affiliation: Division of Radiology, Taipei Municipal Gan-Dau Hospital (Managed by Taipei Veterans General Hospital), No.12, 225 Lane, Zhi-Sing Road, Taipei, Taiwan, 11260. williamyuan.tw@gmail.com.|Department of Radiology, Taipei Veterans General Hospital, No.201, Sec. 2, Shipai Rd., Beitou District, Taipei City, Taiwan, 11217. williamyuan.tw@gmail.com.|School of Medicine, National Yang Ming University, No.155, Sec.2, Linong Street, Taipei, 112, Taiwan. williamyuan.tw@gmail.com.
authors.forename: Wei-Hsin
authors.initials: WH
authors.lastname: Yuan
authors.affiliation: School of Medicine, National Yang Ming University, No.155, Sec.2, Linong Street, Taipei, 112, Taiwan.|Department of Ophthalmology, Taipei Veterans General Hospital, No.201, Sec. 2, Shipai Rd., Beitou District, Taipei City, Taiwan, 11217.
authors.forename: Tai-Chi
authors.initials: TC
authors.lastname: Lin
authors.affiliation: Department of Radiology, Taipei Veterans General Hospital, No.201, Sec. 2, Shipai Rd., Beitou District, Taipei City, Taiwan, 11217.|School of Medicine, National Yang Ming University, No.155, Sec.2, Linong Street, Taipei, 112, Taiwan.
authors.forename: Jiing-Feng
authors.initials: JF
authors.lastname: Lirng
authors.affiliation: Department of Radiology, Taipei Veterans General Hospital, No.201, Sec. 2, Shipai Rd., Beitou District, Taipei City, Taiwan, 11217.|School of Medicine, National Yang Ming University, No.155, Sec.2, Linong Street, Taipei, 112, Taiwan.
authors.forename: Wan-You
authors.initials: WY
authors.lastname: Guo
authors.affiliation: School of Medicine, National Yang Ming University, No.155, Sec.2, Linong Street, Taipei, 112, Taiwan.|Department of Pathology, Taipei Veterans General Hospital, No.201, Sec. 2, Shipai Rd., Beitou District, Taipei City, Taiwan, 11217.
authors.forename: Fu-Pang
authors.initials: FP
authors.lastname: Chang
authors.affiliation: School of Medicine, National Yang Ming University, No.155, Sec.2, Linong Street, Taipei, 112, Taiwan.|Department of Pathology, Taipei Veterans General Hospital, No.201, Sec. 2, Shipai Rd., Beitou District, Taipei City, Taiwan, 11217.
authors.forename: Donald Ming-Tak
authors.initials: DM
authors.lastname: Ho
mesh_terms: D000328:Adult; D004172:Diplopia / Q000209:etiology; D005094:Exophthalmos / Q000209:etiology; D005260:Female; D006106:Granulosa Cell Tumor / Q000150:complications / Q000000981:diagnostic imaging*; D006801:Humans; D008279:Magnetic Resonance Imaging; D009918:Orbital Neoplasms / Q000150:complications / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed
keywords: Computed tomography (CT); Granular cell tumor; Magnetic resonance imaging (MRI); Orbit