Scapular Aneurysmal Bone Cysts in a Cat

Shinya MIZUTANI 1), 2)†, Yuko MIZUTANI 2), Yoshimichi GODA3), Taketoshi ASANUMA1),  Shidow TORISU4), Mika TANABE5) and Yuichi HIDAKA6)

A  7-year-old  spayed female mixed-breed  cat  was  presented  to  our  hospital  with  complaints  of  left  shoulder  swelling,  chronic  lameness  and  severe  pain  in  the  left forelimb.    Radiographic  examination  revealed  that  the  patientʼs swollen left shoulder was due  to a mass lesion of  the left scapula.  A CT scan showed  that  the enlarged  left scapula was accompanied by  the bulging and  thinning of  the cor tical bone and multiple cyst-like structures  in  the lumen.    The  patient  under went left foreleg  amputation  to  relieve  pain.    The  postoperative  course  of  the  patient  was  excellent  and  since  the  surger y  this  cat  has  been free  of  recurrence for more  than  3  years.   Histopathological  examination  revealed  that  the  left  scapular mass  was  aneur ysmal  bone  cysts.    Aneur ysmal  bone  cysts  are  ver y  rare  primar y  tumor-like lesions.   Because  aneur ysmal  bone  cysts  are  distensible  and lytic  bone  lesions, it was considered necessar y  to differentiate  them from other primar y bone  tumors such as osteosarcoma, which present similar imaging findings.