[Fibrous dysplasia of the scull discovered accidently on CT from different indication]

Fibrous dysplasia (dysplasia fibrosa -DF) is a local disorder of spongy bone structure caused by local pathological metabolism. Transformation of trabecular bony structure into connective tissue takes place. Inside the transformed bone scattered connective tissue elements, cartilaginous elements and pathological density are found. The disease proliferates either in the medullary bone or in subperiosteal region, and the development of fibrous tissue causes bone expansion with thinning of overlying cortex. The radiological appearance depends on the stage of the disease. The margins of the lesions are usually obscured and gradually turn into pathological tissue of trabeculated appearance.

The aim of the study is to demonstrate fibrous dysplasia that is accidentally found during radiological diagnostics of facial skeleton and stomatological disease, and to describe radiological appearance of the pathological lesions.

The material included 23 patients (9 males, 14 females), of 24 to 64 years of age, that were directed for the diagnostics of facial skeleton and stomatological disease with the use of multislice computer tomography, because of clinically diagnosed pathologies in the nasal sinuses, temporomandibular joints, pathologies of the mandible and maxillary, and before treatment with prosthetic implants. All the presented fibrous dysplasia cases were diagnosed during the performance of the above examinations. The examinations were performed by the use of spiral CT (Siemens Somatom Sensation 10) with standard parameters. The range of the examination included the nasal sinuses, facial skeleton or the whole scull-configuration of the detectors 10 x 0.75 mm, slice thickness 1 mm, reconstruction gap 0.7 mm, kernel H60s for osseous structure evaluation, and slice thickness 1, 4 do 4 mm, reconstruction gap 4 mm, kernel H31s for soft tissue evaluation. The obtained results were presented sented in the form of figures.

In the analyzed material 23 cases of scull fibrous dysplasia were found. The disease involved 9 males (39.14%) and 14 females (60.86%) from 24 to 64 years of age. Mean age for the whole group was 46.6 years, for males was 50,5 years and for females was 44.4 years. Females with fibrous dysplasia were more numerous (60.86%) than males (39.14%). Monoostotic dysplasia was found in 18 cases (78,89%), polyostotic dysplasia was found in 4 cases (13.05%), the skull-face dysplasia was found in 9 cases (14.07%). The radiological appearance is characterized by lesions that unclearly and gradually turn into pathological tissue with different densities, trabeculated appearance, and sclerotic, lytic or mixed structure. Early lesions usually have lower density than the normal surrounding bone, giving the appearance of translucency.

Fibrous dysplasia of the facial skeleton is most commonly incidentally found on CT examinations of the head, mandible and nasal sinuses. Diagnosis of fibrous dysplasia is important because of unfavorable influence of the disease on stomatognathic system, laryngological disease, ophthalmic and neurological disease.