The findings suggest a pedunculated chondroid lesion arising from the internal aspect of the right sphenoid wing, most likely chondrosarcoma. The appearance of the calcifications would be very atypical for meningioma and chondromyxoid fibroma which are the main differential diagnoses. 

MRI is shown first on purpose as the CT-scan best demonstrates the underlying chondroid matrix ― less definite and much more puzzling on MRI.

Histopathology

Microscopic description:

• lobules of cartilage and some moderately cellular myxoid stroma extensively permeating and disrupting lamellar bone
• lobules of cartilage are of low to moderate cellularity and the chondrocytes show mild and moderate cytologic atypia
• there are foci of old necrosis with infiltration by foamy histiocytes
• no cytologic atypia is seen in the bone

Final diagnosis: Intermediate chondrosarcoma (grade II)