Massive Hyperostotic Meningioma En Plaque Mimicking Fibrous Dysplasia

The authors report an extremely rare case of a massive hyperostotic meningioma en plaque, which had characteristics of unique bony growth. A 34-year-old man presented with a palpable solid mass in the left cranial region that had gradually grown in size with a broad base on the calvarium for 8 years. Radiologically, the area involved by the mass ranged from the sphenoid bone to the frontal, parietal, temporal, and occipital bones. Three-dimensional CT revealed multiple growing spiculate features on the inner and outer cranial surface. Even though the radiologic features resembled fibrous dysplasia, it was histologically found to be a type of meningioma.