Case Study: June 2013


  • 35 year old West African male
  • Axial proptosis
  • Cystic mass, intraconal on imaging
  • Removed
  • Macroscopicially, well-defined solid white mass with haemorrhagic ‘cystic’ areas
  • Fig 1 and 2-H and E
  • Fig 3 CD34
  • Fig 4-bcl2
  • Fig 5-CD99


  1. What do Fig 1 and 2 display?
  2. With the immuno-profile, what is the diagnosis?
  3. What is the histological differential?
Click to show answers
  1. Dilated vessels within a tumour composed of bland spindle cells invested by delicate collagen
  2. This is an orbital solitary fibrous tumour (SFT). The histology in this case was bland. Recently, a new gene fusion has been described (NAB2-STAT6)
  3. Would include giant cell angiofibroma, neurofibroma and schwannoma all with degenerative ‘cystic’ change


  • Whole-exome sequencing identifies a recurrent NAB2-STAT6 fusion in solitary fibrous tumors. Chmielecki J, Crago AM, Rosenberg M, O’Connor R, Walker SR, Ambrogio L, Auclair D, McKenna A, Heinrich MC, Frank DA, Meyerson M.
    Nat Genet. 2013 Feb;45(2):131-2
  • Identification of recurrent NAB2-STAT6 gene fusions in solitary fibrous tumor by integrative sequencing.Robinson DR, Wu YM, Kalyana-Sundaram S, Cao X, Lonigro RJ, Sung YS, Chen CL, Zhang L, Wang R, Su F, Iyer MK, Roychowdhury S, Siddiqui J, Pienta KJ, Kunju LP, Talpaz M, Mosquera JM, Singer S, Schuetze SM, Antonescu CR, Chinnaiyan AM. Nat Genet. 2013 Feb;45(2):180-5.