Pituitary adenomas are numerically the most significant of the sellar/parasellar lesions, but they represent only one of a multitude of pathologic processes occurring in the area (1). Around the modest confines of the sella turcica are several intricate anatomical structures of neural, endocrine, vascular, osseous, and meningeal origins. It is remarkable that such morphologic and functional diversity can be so intimately represented in such a discrete area of the neuroaxis, and

From: Management of Pituitary Tumors: The Clinician's Practical Guide, Second Edition Edited by: M. P. Powell, S. L. Lightman, and E. R. Laws, Jr. © Humana Press Inc., Totowa, NJ

that accompanying each anatomic component is a correspondingly diverse set of pathologic processes. A sprinkling of embryonic "rests" sequestrated in the vicinity provide the substrate for various sequelae of disordered embryogenesis. Surrounding neural, meningeal, and mesenchymal tissues further contribute an assortment of tumor types, so that few forms of intracranial neoplasia escape representation in the sellar and parasellar regions.

The spectrum of pathologic possibilities is supplemented further by a collection of nonneoplastic "tumor-like" afflictions, which can involve any of a variety of sellar region structures. Many of these are inflammatory in nature, ranging from acute suppuration to chronic granulomatous conditions to autoimmune processes. Others are structural abnormalities, such as the empty sella syndrome and aneurysms of the internal carotid artery. Although pituitary adenomas are the most common mass lesions encountered in the sellar region, several other pathologic processes do periodically involve the area. Because many of these conditions may mimic, clinically and radiologically, seemingly ordinary pituitary adenomas, both the clinician and the pathologist must always be prepared for unusual and, at times, unexpected pathology when approaching lesions of the sellar and parasellar regions.

In this chapter, we review the diagnosis and management of sellar and parasellar lesions, exclusive of pituitary adenomas. It is important to recognize that despite the etiologic, pathologic, and biologic diversity of the various tumor and tumor-like conditions represented in the sellar region, most are unified by a fairly generic pattern of clinical presentation—one dominated by the predictable ophthalmologic, endocrinologic, and neurologic sequelae of a sellar region mass. Furthermore, because many of these lesions share overlapping radiologic features—ones that frequently mimic seemingly typical pituitary adenomas— definitive preoperative diagnoses are often difficult to establish with certainty. Nonetheless, such distinctions should, if possible, be made because accompanying each of the different pathologic processes of the sellar region (Table 1) may be a different set of diagnostic and therapeutic imperatives that affect prognosis.

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