Seeded Metastases

The distribution of seeded metastases within the abdomen, as discussed in Chapter 4, has been shown to follow the dynamic pathways of the circulation of ascitic fluid.15-17 The malignant cells are shed by the primary neoplasm and then transported by the ascites. They are then deposited and subsequently grow as seeded metastases at the sites of stasis or pooling of the ascitic fluid. In the midabdomen, pooling occurs within the peritoneal recesses of the mesenteric ruffles.18 Flow occurs in a series ofrivulets or cascades from one mesenteric recess to the next lower, with the largest and most consistent pool formed at the termination of the small bowel mesentery at the ileocolic junction. The seeded metastases lodge and grow, therefore, on the mesenteric borders and involve distal ileal loops in over 40% of all cases.16

The distinctive radiologic feature lies in the localization of changes to the mesenteric border of distal ileal loops, evident in over 75% of seeded metastases in the right lower quadrant of the abdomen.2 Mass changes and associated desmoplastic tethering of mucosal folds constitute the basic characteristics. Figure 14-26 illustrates multiple masses indenting the mesenteric borders of individual distal ileal loops in a case of seeded metastases from carcinoma of the ovary. They are strikingly oriented in relation to the axis of the small bowel mesentery. The associated desmoplastic response, another sign highly distinctive of seeded lesions,18 results in angulated tethering of the mucosal folds on the mesenteric borders only. Angulation of the loops themselves at the sites of the serosal masses on the mesenteric borders (Fig. 1427) further indicates the desmoplastic process.

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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