The ‘Eye Mask Sign’ in Fibrous Dysplasia on 99m Tc-MDP Skeletal Scintigraphy and SPECT/CT

Fibrous dysplasia (FD) is a fibro-osseous disorder that manifests with distinct or overlapping clinical patterns. FD may bemonostotic or polyostotic and commonly associated with syndromes such as McCune-Albright syndrome and Mazabraudsyndrome. We report a case of polyostotic FD with bilateral involvement of craniofacial bones in a distinct pattern and proposethis characteristic appearance as the ‘eye mask sign’ on 99mTc-Methylene Diphosphonate (MDP) skeletal scintigraphyand SPECT/CT. Other unusual skeletal scintigraphic features noted in this case are also described (Figs. 1, 2, and 3).