Mesenteric mass in the right lower quadrant with calcifications, desmoplastic reaction, and arterially enhancing liver metastases is characteristic of carcinoid tumor of the small bowel. The primary tumor is not seen in this case, and most commonly in the ileum. 

Given the narrowing of the SMA/SMV at the level of the mass, some degree of mesenteric ischemia may also be present. This likely contributes to the degree of small bowel dilation with wall thickening. 

There is peritoneal carcinomatosis, evidenced by multiple pelvic nodules.