Fibrous Dysplasia of the Sphenoid Sinus: a Case Report

Introduction: Fibrous Dysplasia (FD) is an uncommon disease, with an unknown etiology, that causes an alteration in the normal osteoblastic function of the bony tissue, resulting in substitution of the regular bony tissue, for an abnormal fibrous tissue. It is more prevalent in the first three decades of life.

Case Report: We present the case of an 11-year-old caucasian female patient, with a history of headache and chronic nasal obstruction. CT scan evidenced an infiltrative bony lesion in the sphenoid sinus, as well as in the cribiform plate. The patient was operated through an endoscopic endonasal approach. The anatomo-pathological examination evidenced bony fragments with trabecullae and erratic alignment, and osteoblastic borders. The stroma was composed by fibrovascular connective tissue, consistent with FD.

Discussion: FD is a skeletal disturbance characterized by excessive proliferation of the fibrous tissue in the bone marrow, resulting in osteolytic lesions, fractures and deformities in the affected bone. The prevalence is 2.5% of all bone tumors and 7% of the benign tumors. It can be monostheotic (involvement of only one bone or contiguous bone – 70% of cases) or poliostheotic (involvement of multiple bones). There is a third form, called McCune-Albright Syndrome (involvement of multiple bones, skin hyperpigmentation and endocrine disturbances). The incidence of craniofacial involvement is from 10 to 25% in the monostheotic form of the disease. Usually the affected areas are the mandible and maxillae, but it is reported in the frontal, sphenoid and temporal bones. Lesion inside the sphenoid sinus is a rare condition. Symptoms vary according to the location of the bony lesions, and compression of structures due to the mass effects. Patients can be asymptomatic, may present headache, craniofacial deformities and cranial nerve paralysis.

Conclusion: FD is a disease of young patients, usually with a slow and asymptomatic grown, but, according to the location, it can infiltrate and compress vital structures. The diagnosis is established through clinical, radiological and histological features. Treatment should be individualized, ranging from expectant to gross total surgical removal. Since these lesions have imprecise limits and a recidivant behavior, it is important that the resection should be maximum. Radioterapy is avoided due to the risk of malignant transformation.

No conflict of interest has been declared by the author(s).