Intraperitoneal Spread of Malignancies

The spread of neoplasms within the peritoneal cavity occurs by direct invasion, intraperitoneal seeding, embolic metastases, and lymphatic extension.1,2 Recent insights and basic correlation with the pathogenesis of the intraabdominal spread of malignancies have established that the pattern of involvement and the individual effects of secondary malignancies of the bowel often present characteristic radiologic features. 1,3-6 These reflect the mode of dissemination and thereby indicate the primary site. They are based on the application of certain gross anatomic relationships, the dynamic factors of the flow of ascites, and conditions of hematogenous dissemination.

Distinction between the major pathways of spread (Table 4-1) is of critical practical importance for several reasons: (a) It closely correlates the radiologic changes with the pathogenesis and provides a rational system for radiologic analysis, (b) Since it is not rare for a malignant neoplasm to be manifested initially by its gastrointestinal metastasis or extension,7 recognition of the type of secondary involvement can aid in the search for the primary

Table 4-1. Classification of Pathways of Spread of Secondary Neoplasms to the Bowel

Direct invasion

From noncontiguous primary tumors Along mcscnteric reflections By lymphatic permeation From contiguous primary tumors Intraperitoneal seeding Embolic metastases lesion. Confronted with a lesion of the bowel that can be identified as secondary in nature, the clinical radiologist is then in a crucial position—by recognizing the particular mode of dissemination—to determine the further investigation required in the search for the primary lesion. (c) If there is a known primary tumor and gastrointestinal symptomatology develops, particular radiologic attention can be directed to the most likely sites in the abdomen for that type of lesion. In a patient with either a known or clinically occult primary malignancy, only nonspecific abdominal symptomatology may herald the development of intraperitoneal metastases. Not infrequently, these are attributed to other gastrointestinal disorders or perhaps to the side effects of chemotherapeutic drugs. (d) Identification of the type of secondary involvement of the bowel can help in planning treatment. Awareness that involvement of a portion of the alimentary tract is secondary to invasion from an adjacent primary tumor allows for adequate preopera-tive preparation for wider surgical excision. Localized embolic metastases are subject to segmental resection.7,8 Radiotherapy and chemotherapy may be reserved for disseminated metastases or implants.

Analysis of a large proved series1 has demonstrated that each of the three major pathways of spread (direct invasion, seeding, and hematogenous metastases) accounts for roughly an equal number of cases of secondary neoplastic involvement of the bowel. Occasionally, more than one mechanism of spread may be encountered in any given patient. This is seen most frequently in intraperitoneal primary malignancies with both direct invasion and seeded metastases.

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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