Abstract
The term fibrous dysplasia was first used in 1938, is a bone lesion in which the spongy bone is replaced by fibrous tissue. Asymptomatic for a long time and is most often discovered accidentally during a routine radiological examination or following a complication. The case we presented here is interesting of its management but also its long monitoring.
A young woman 27-year-old, with no history of pathology, consulted for a painful low-left cheek swelling, asymmetry facial with a palpable tumor painless, fixed, adhering to the mandible. The endobucal examination recovered a filling of the lower vestibular cheek, without dental mobility or labio-mental hypoesthesia. The orthopantomogram and the computed-tomography showed an heterogeneous image well limited, polylobed in contact with the dental alveolar canal. A resection by endobuccal route was performed .The Diagnosis of fibrous dysplasia was confirmed by histological study . No recurrence was noted 26 months after surgery with regular clinical and radiological following since.
The cranio-facial localizations are in order of frequency: occipital, parietal, zygomatic, mandibular, maxillary, ethmoidal, sphenoidal, frontal, and temporal. The diagnosis is difficult to make from clinicoradiological data, confirmed only by the anatomopathological study. Histologically, there are three types. In our case, histology had recovered the monostotic type. Evidently, sarcomatosis transformation has been well described in reason why the annual monitoring is desirable to detect earlier any recurrence or malignant transformation.
The localization in the craniofacial sphere deserves special attention. The prognosis of fibrous dysplasia lesions is generally good due to the stabilization trend.

Key words: Fibrous dysplasia, Mandible, Complications, Surgical treatment