Characterization of sellar and parasellar lesions is challenging due to the anatomical complexity of the skull base, the extensive breadth of pathology that one may encounter, and the similar imaging appearance and clinical presentations of some entities. The presence of various critical neurovascular structures in a confined space complicates surgical access for tissue diagnosis or resection and underscores the importance of appropriate imaging. We review relevant neuroimaging aspects of sellar and parasellar lesions with particular attention to the anterior skull base.
RELEVANT ANATOMY AND EMBRYOLOGY
The adenohypophysis derives from a diverticulum that arises from the primitive oral cavity (Rathke’s pouch) and projects toward the central skull base at around weeks 4 and 5.1,2 A diencephalic infundibulum then projects inferiorly and contacts the diverticulum, which loses its connection to the oral cavity.2 The anterior wall of the pouch fills with cells and forms the pars distalis, leaving a small cleft between it and the posterior wall, which becomes the pars intermedia.3 A small infundibular process grows superiorly and becomes the pars tuberalis.2 The posterior diencephalic tissue evolves into the neurohypophysis.4