title: Cystic bone lesions: histopathological spectrum and diagnostic challenges.
abstract: OBJECTIVE
  Bone cysts are benign lesions occurring in any bone, regardless of age. They are often asymptomatic but may cause pain, swelling, fractures, and local recurrence and may be confused with other bone lesions.
  
  
  METHODS
  We retrospectively re-evaluated 143 patients diagnosed with aneurysmal bone cyst (n=98, 68.5%), solitary bone cysts (n=17 11.9%), pseudocyst (n=10.7%), intraosseous ganglion (n=3, 2.1%), hydatid cyst (n=2; 1.4), epidermoid cyst (n=1, 0.7%) and cysts demonstrating "mixed" aneurysmal-solitary bone cyst histology (n=12, 8.4%), and compared them with nonparametric tests.
  
  
  RESULTS
  Aneurysmal bone cyst, solitary bone cysts and mixed cysts were frequently seen in the first two decades of life while the others occurred after the fourth decade. Aneurysmal bone cysts, intraosseous ganglion and pseudocysts were more common in women contrary to solitary bone cyst and mixed cysts (the female/male ratio was 1.22, 2 and 1.5 versus 0.7 and 0.5, respectively). Aneurysmal bone cyst, solitary bone cysts and "mixed" cysts were mostly seen in long bones, predominantly the femur, while epidermoid, hydatid and pseudocysts were all seen in flat bones like the vertebra, pelvis and mandible (p=0.001, chi-square). Repeat biopsies were performed in 19 cases (13.3%), 84.2% of which were aneurysmal bone cyst (5 conventional, 9 solid, 1 secondary and 1 subperiosteal) and three (15.8%) were mixed cysts (p=0.02, chi-square). Notably, some of them were located in inaccessible areas of pelvis (n=3), femur (n=3) and maxilla (n=2).
  
  
  CONCLUSIONS
  The most common and challenging intraosseous cysts are aneurysmal bone cysts, particularly the "solid" variant. The "mixed" aneurysmal-solitary bone cyst "subgroup" requires further research with larger series to be defined more thoroughly.
authors: Department of Medical Pathology, Ege University Faculty of Medicine, İZMİR, TURKEY.
authors: Başak
authors: B
authors: Doğanavşargil
authors: Ezgi
authors: E
authors: Ayhan
authors: Mehmet
authors: M
authors: Argin
authors: Burçin
authors: B
authors: Pehlivanoğlu
authors: Burçin
authors: B
authors: Keçeci
authors: Murat
authors: M
authors: Sezak
authors: Gülçin
authors: G
authors: Başdemir
authors: Fikri
authors: F
authors: Öztop
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D001706:Biopsy; D001845:Bone Cysts / Q000473:pathology*; D017824:Bone Cysts, Aneurysmal / Q000473:pathology*; D002648:Child; D002675:Child, Preschool; D004443:Echinococcosis / Q000473:pathology*; D004814:Epidermal Cyst / Q000473:pathology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D012189:Retrospective Studies; D012737:Sex Factors; D055815:Young Adult