title: Assessment of 120 maxillofacial aneurysmal bone cysts: a nationwide quest to understand this enigma.
abstract: OBJECTIVE
  Compared with other maxillofacial lesions, oral and maxillofacial (OM) aneurysmal bone cysts (ABCs) are rare, and most studies have been case reports. Because the features or radiographic findings of 1 case could not be representative of the whole, conclusions cannot be drawn and data analyses will not be feasible. Our aim was to assess and describe the clinical and histopathologic characteristics of a large sample of subjects with ABCs. To our knowledge, the present case series of OM ABCs is the largest ever reported.
  
  
  METHODS
  To address our research purpose, we designed and implemented a retrospective case series. A multicenter retrospective cohort study of patient charts dated from 1967 to 2013 (46 years) at 10 major universities in 8 cities was undertaken to assess OM ABCs nationwide. Subjects were included if they had documented chart data and definitive histopathologic slides confirming the diagnosis and treatment of ABC. They were excluded if their histopathologic slides did not confirm the diagnosis of an ABC. Data were collected, and special forms were completed. Variables such as age, gender, site (ie, maxilla, mandible, anterior, posterior), histologic type (ie, solid, mixed, vascular), signs, symptoms, radiographic features (ie, radiolucency, unicystic or multilocular), and outcomes (ie, treatment modal, recurrence, complications) of the lesion were evaluated and documented by OM surgeons and confirmed by OM pathologists for assurance. Data analyses were performed using Statistical Package for Social Sciences, version 20, software (SPSS, Chicago, IL) (P < .05).
  
  
  RESULTS
  We assessed the medical records and histopathologic slides of 120 patients diagnosed and treated for OM ABCs nationwide. Of these patients, 69 were male (57.5%) and 51 were female (42.5%), with no predilection found. The key findings were as follows. The mean age of occurrence was 20.7 ± 2.5 years (range 4 to 78), and occurrence was significantly greater in the first 2 decades of life (P < .001). The incidence was 2.6 cases/year. ABCs were significantly more common in the mandible (P < .05) and posterior areas (P < .05). The most common histopathologic type was the mixed type (P < .05). Firm swelling was the most common clinical presentation (P < .05); all cases were radiolucent and commonly unilateral (P < .05). Most were treated by excision and curettage. Recurrence was reported in 11 patients (9.2%) during the follow-up period (1 to 45 years).
  
  
  CONCLUSIONS
  The present retrospective cohort found ABCs with a variable presentation, disease course, and histopathologic type, with no gender predilection. ABCs were significantly more common in childhood and adolescence and in the mandible and posterior areas of the jaws. Of the cases reviewed, 90% were treated by excision and curettage. ABCs had a relatively low recurrence rate (<10%), precluding the need to perform aggressive surgery primarily.
authors.affiliation: Professor, Department of Oral and Maxillofacial Surgery, Trauma Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran. Electronic address: motamedical@yahoo.com.
authors.forename: Mohammad Hosein Kalantar
authors.initials: MH
authors.lastname: Motamedi
authors.affiliation: Postgraduate Student, Orthodontics Department, Faculty of Dentistry, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Ahmad
authors.initials: A
authors.lastname: Behroozian
authors.affiliation: Assistant Professor, Department of Oral and Maxillofacial Pathology, Baqiyatallah University of Medical Sciences, Tehran, Iran.
authors.forename: Taghi
authors.initials: T
authors.lastname: Azizi
authors.affiliation: Assistant Professor, Department of Oral Pathology, School of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran.
authors.forename: Ali Dehghani
authors.initials: AD
authors.lastname: Nazhvani
authors.affiliation: Assistant Professor, Department of Oral and Maxillofacial Pathology, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Pouria
authors.initials: P
authors.lastname: Motahary
authors.affiliation: Assistant Professor, Department of Oral and Maxillofacial Pathology, Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Ali
authors.initials: A
authors.lastname: Lotfi
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D017824:Bone Cysts, Aneurysmal / Q000473:pathology*; D002648:Child; D002675:Child, Preschool; D005145:Face / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008437:Maxilla / Q000473:pathology*; D008875:Middle Aged; D012189:Retrospective Studies