Fibrous dysplasia (orbital roof)

Case contributed by A.Prof Frank Gaillard



Patient Data

Age: 30 years
Gender: Female

An expansile intraosseous lesion is located along the medial aspect of the right orbital root midway between the apex and the orbital rim. It is of intermediate T1 signal, vividly heterogeneously enhancing, with a central high T2 signal region and lower signal periphery. 

No other lesion seen in the orbits. There is no significant mass effect on the orbital contents and frontal lobe. Anterior visual pathway are unremarkable. 

Expansile intraosseous lesion of the right orbital roof demonstrates ground glass opacity on bone window, typical of fibrous dysplasia. 

Case Discussion

The patient went on to have surgery.


MICROSCOPIC DESCRIPTION: Paraffin sections show fragments of moderately hypercellular tissue. These contain haphazardly arranged and irregularly shaped trabeculae of woven bone, some with incomplete osteoblastic rimming. Spaces between trabeculae are filled with a loose fascicular and storiform arrangement of spindle cells. These have uniform nuclear features. No mitotic figures or areas of necrosis are seen. Immunohistochemistry shows weak positive staining for smooth muscle actin (SMA) in the spindle cells. No staining for epithelial membrane antigen (EMA) or progesterone receptor (PgR) is seen. The features are of fibrous dysplasia. No evidence of malignancy is seen.

FINAL DIAGNOSIS: fibrous dysplasia.

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Case information

rID: 39826
Published: 24th Dec 2016
Last edited: 22nd Jul 2017
Inclusion in quiz mode: Included

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