Senior cat with large intestinal mass and hyperechoic mesentery: peritonitis? carcinomatosis?

* 13 yo cat, weight loss, mild decrease in appetite, large abdomen. No fever.

* Leukocytosis (WBC 27) with neutrophilia 22251), monocytosis (3846), low albumin (2.2), low TP (4.8), mild increase of ALP (84). 

* Large (5.5cm long by 3cm wide) heterogeneous hypoechoic intestinal mass with total loss of layers: lymphoma vs carcinoma.

* All intestines are thickened with a prominent muscularis: lymphoma vs other.

Senior cat with large intestinal mass and hyperechoic mesentery: peritonitis? carcinomatosis?

* 13 yo cat, weight loss, mild decrease in appetite, large abdomen. No fever.

* Leukocytosis (WBC 27) with neutrophilia 22251), monocytosis (3846), low albumin (2.2), low TP (4.8), mild increase of ALP (84). 

* Large (5.5cm long by 3cm wide) heterogeneous hypoechoic intestinal mass with total loss of layers: lymphoma vs carcinoma.

* All intestines are thickened with a prominent muscularis: lymphoma vs other.

* Severely rounded hypoechoic mesenteric LN (8mm wide) due to neoplasia vs reactive.

* Scant anechoic peritoneal effusion due to GI neoplasia vs FIP (unlikely given age).

* Large liver, GB sludge.

* Hyperechoic almost nodular mesentery everywhere. Do you think it is due to peritonitis? steatitis? carcinomatosis? (or lymphomatosis?)

* Pancreas: hyperechoic fat around the R pancreas/duodenum. Pancreatitis? pancreatic tumor?

* Owner declined FNA of mass/LN. I would recommend steroids for the neoplasia, but I am concerned about the possible peritonitis. P ate with appetite after the scan.

Thank you for your help!