Conversion of aneurysmal bone cyst into fibrous dysplasia: a rare pediatric case report



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Journal of maxillofacial and oral surgery, 0974-942X, Vol. 15, 2016, p. 355-360

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Aneurysmal bone cyst (ABC) is an uncommon, non-neoplastic, expansive and erosive bone lesion. Considered as a pseudocyst due the lack of epithelial lining, the presence of giant cells and similarity to other lesions can make preoperative diagnosis difficult; biopsy findings must be co-related to complete clinical and radiological assessment. ABC’s controversial etiopathogenesis and variable clinicopathological presentations have been widely described, but to date, there are just a few reports in literature describing the development of fibrous dysplasia (FD) from an ABC, and even less cases occurring in the jaws. We describe the case of an ABC in an 8 year-old male patient, affecting the body of the mandible, which showed accelerated growth associated to thinning of the buccal, lingual and lower cortical plates. The treatment consisted of repetitive surgical resection, curettage of the lesion and mandibular reinforcement with osteosynthesis reconstruction plates. A 16-month follow-up showed self-limitation of the overgrowth. The final histopathological and radiological analysis confirmed the FD diagnosis. First described by Van Arsdale in 1893 as ossifying hamartoma, but renamed later by Jaffe and Liechtenstein, the aneurysmal bone cyst (ABC) is a non-neoplastic, expansive and erosive bone lesion [1]. Infrequent within the craniofacial skeleton, the ABC was initially described as a long bone and cervical column pathology [2]. In 1958, Bernier and Bhaskar reported the first case occurring on the jaws, and until 2012, only 121 cases were described involving facial bones [3]. The etiopathogenesis of this entity remains controversial, but it has been described as a consequence of traumatism, as hemodynamic alteration, or as a secondary phenomenon associated to the presence of primary bone lesions [4]. It can be classified as primary or secondary, depending on the presence or absence of associated pre-existing histopathological conditions, such as the ossifying fibroma or the central giant cell granuloma, among others, being the first and the most frequently involved [5]. Several articles tried to describe the association between the ABC and the fibrous dysplasia (FD), another type of fibro-osseous lesion; however, cases occurring within the jaws are difficult to find; moreover, the development of a FD from an ABC is even harder to find. This article presents an extensive mandibular ABC case in a pediatric patient, which followed an unexpected behavior after more than 2 years, 4 interventions, and a 16 month follow-up period. The final histopathologic analysis and its current stabilization (that suggests self-limiting of the growth process) are strongly indicative of FD conversion.

Palabras clave


Aneurysmal bone cyst, Fibrous dysplasia, Jaws


Displasia fibrosa ósea
Huesos Faciales