Diseases of the Peritoneum, Retroperitoneum, Mesentery, and Omentum

The visceral peritoneum, from the splanchnic layer, covers the intra-peritoneal organs and forms the mesenteries by which they are suspended. Tuberculous peritonitis involves the parietal and visceral peritoneum, as well as the omentum, intestinal tract, liver, spleen, and female genital tract. Primary retroperitoneal tumors should be differentiated from other masses in the region, including renal lesions, pancreatic cysts and tumors, malignancies of the gastrointestinal tract, ovarian tumors, and cysts of the omentum and mesentery. This chapter describes some of the diseases such as mesenteric panniculitis, retractile mesenteritis and mesenteric fibromatosis that primarily or prominently involve the omentum, mesentery, or both mesenchymal structures. Lymphangiomas are most often located in the small bowel mesentery but occasionally may be found in the mesocolon, the omentum, or, more rarely, the retroperitoneum. Malignant tumors of the mesentery and omentum spread by local invasion and peritoneal implantation leading to encasement of viscera and subsequent obstruction.