In most organs of the body, the shape of a tumor radiologically demonstrated is not helpful in the preoperative histologic diagnosis. By virtue of its concentric growth, a noninfiltrative neoplasm tends to assume a spherical configuration. The parent organ usually offers no constant asymmetry contributing to a characteristic shape of a tumor developing within it. The adrenal glands are virtually unique in this respect. A specific radiologic diagnosis may frequently be indicated by a geometric appreciation of the alterations in outline produced by a neoplasm developing within either of the gland's two distinct components. Anatomic Considerations Triangular in outline, although the left may be crescentic, the adrenal glands are composed of a medulla and a cortex. The medulla resides within the base of the gland and the major portion of the cortex (80 to 90 per cent) lies in the apex (7). In fact, the apex of the adrenal gland is composed of cortical tissue only. Therefore, the cortex and medulla occupy rela...