The cranial base has distinct embryologic origins. The anterior cranial base is derived solely from the neural crest, similar to other facial bones, whereas the posterior cranial base is formed by the paraxial mesoderm. Both these parts also develop and grow with distinct features. Unlike other craniofacial bones that are mostly formed through intramembraneous ossification, the cranial base is formed through endochondral ossification, in which a cartilage plate, known as the chondrocranium, is formed first and soon replaced by bones. Individual bones are then connected by cartilaginous structures, termed synchondroses, which are morphologically similar to long-bone growth plates.
These processes justify the presence of a disembryogenic cyst in the sphenoid bone. The authors present a case of a clival-sphenoidal region neoformation treated with a transnasal-endoscopic approach.