Co-existing fibrous dysplasia and atypical lymphoplasmacyte-rich meningioma

We report an unusual and extremely rare case of coexisting fibrous dysplasia of the sphenoid sinus with atypical lymphoplasmacyte rich meningioma (World Health Organization Grade II), right frontal lobe in a 25-year-old male. The patient presented with history of generalized tonic clonic seizures with a loss of vision in the right eye. Radiologically it was seen that the sphenoid sinus lesion was sclerotic and was extending and causing compression of the optic nerve. Magnetic resonance imaging revealed mass lesion in the right frontal lobe, iso to hypointense on T₁ weighted images and hyperintense on T2 weighted images with uniform contrast enhancement. Clinically and radiologically the possibility of fibrous dysplasia of the sphenoid bone and sinus with metastases in the frontal lobe from a different primary was considered. On histopathology the frontal lobe lesion showed a tumor composed of cells with vesicular nuclei, focal nuclear pleomorphism, a mitotic rate of = 4/10 high power field and a single focus of necrosis. The cells were arranged in fascicles and had a prominent lymphoplasmacytic infiltrate. In contrast, the sphenoid sinus lesion was composed of narrow, curved bony trabeculae with a characteristic fishhook configuration without osteoblastic rimming and interspersed with fibrous tissue of variable cellularity. Although no definite causative factors are described for the coexistence of these tumors, however, a common yet undetermined denominator in the origin has been proposed in the literature.