Carcinoid Tumors

Almost 90% of intestinal carcinoids occur in the distal ileum.20,21 Invasion through the intestinal wall may stimulate an intense desmoplastic reaction in the surround ing submucosa and mesentery. A characteristic manifestation is a mesenteric mass with radiating linear strands22 (Figs. 14-29 and 14-30).

Ileal carcinoids are multiple in approximately one-

third of cases. Most comprise more than three lesions, while in a small percentage dozens of lesions of variable sizes may stud a discrete segment of the bowel.20,21 Although they may be separated by several centimeters, skip areas are uncommon. These multiple lesions are considered by Warner et al. to be secondary mucosal deposits rather than independent primaries.26 Previously viewed as multicentric neoplastic foci, meticulous analysis suggests that the phenomenon reflects mucosal metastases from a dominant parent carcinoid tumor, occurring as a process of retrograde submucosal lymphatic spread. Multiple carcinoid tumors thus show a strong predilection for the antimesenteric border of the small intestine.26

Fig. 14—28. Hematogenous metastatic melanoma.

A large submucosal mass with a prominent central ulceration is localized to the convex, antimesenteric margin of a distal jejunal loop. (Reproduced from Meyers.2)

Fig. 14—29. Carcinoid of the ileum.

CT demonstrates a round 2-cm mesenteric mass with stellate radiation of fibers toward the adjacent mesentery and borders of loops. The wall of the involved loop is thickened and angulated. The mass shows a discrete central calcification, and a small lymph node is present in the adjacent tissue.

(Reproduced from Maccionni et al.23)

Carcinoid Radiology

Fig. 14—30. Carcinoid of the ileum.

(a) CT shows a mesenteric mass (arrow) with emanating strands corresponding to thickened neurovascular bundles.

(b) Corresponding gross specimen after surgical resection confirms the mesenteric location of the tumor. (Reproduced from Pelage et al. )

Fig. 14—30. Carcinoid of the ileum.

(a) CT shows a mesenteric mass (arrow) with emanating strands corresponding to thickened neurovascular bundles.

(b) Corresponding gross specimen after surgical resection confirms the mesenteric location of the tumor. (Reproduced from Pelage et al. )

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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