McCune-Albright syndrome with polyostotic fibrous dysplasia

Case contributed by Mustafa Takesh
Diagnosis almost certain


Known McCune-Albright syndrome, presented with right mild proptosis.

Patient Data

Age: 3 years
Gender: Female

Multiple areas of fibrous dysplasia involving the craniofacial skeleton, in particular circumferentially around the right orbit with asymmetric size and shape of the orbits.

There are multiple areas of fibrous dysplasia with classic ground-glass density, involving the bilateral temporal bone, right great and lesser wing of sphenoid, right aspect of the clivus, bilateral maxillary bone, right ethmoid bone, right frontal bone and right pterygoid plates. 

Subsequently, there is narrowing of the right optic canal, right superior orbital fissure and right foramen rotundum. 

Confirmation of extensive skull base disease with bone expansion, in particular circumferentially around the right orbit, leading to reduced size of the right orbit and proptosis. In addition, there is narrowing of the optic nerve canal.

Case Discussion

3 year old girl with known McCune-Albright syndrome, confirmed by molecular genetic testing on ovarian sample through identification of GNAS 1, presented with prominent right eye.  She is known to have pituitary microadenoma and GH oversecretion.

All imaging modalities showed typical areas of fibrous dysplasia involving the craniofacial skeleton, in particular circumferentially around the right orbit, which explains the clinically observed proptosis.

Fibrous dysplasia (FD) is an uncommon disorder characterized by replacement of normal bone with fibro-osseous tissue. If the fibrous dysplasia is associated with extraskeletal disorders such as hyperfunctioning endocrinopathies and hyperpigmented skin lesions (café-au-lait macules), it will be called McCune-Albright Syndrome (MAS).

The diagnosis of FD/MAS is based on having two or more typical clinical features or identification of GNAS by molecular genetic testing. FD/MAS is not inherited, so no family testing is required.

In case of MAS, the fibrous dysplasia might range from monostotic to advanced polyostotic disease, involving in particular the craniofacial and axial skeleton and leading to progressive scoliosis, facial deformity, and loss of vision/ hearing.

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