Ultrasonography of intestinal mast cell tumors in the cat.

The sonographic features of intestinal mast cell tumors (MCT) were reviewed in 14 cats. The mean age was 13.4 ± 2.5 years. There were 16 focal intestinal tumors and one diffuse submucosal infiltrate. The most common pattern was focal, hypoechoic wall thickening that was noncircumferential and eccentric (9/16 tumors) or circumferential, asymmetric, and eccentric (5/16 tumors). Nine of the cats had lesions in the jejunum or duodenum, four were at the ileocecocolic junction, and one cat had a colonic mass. Six MCTs had altered but not loss of wall layering, and the most commonly affected layer on ultrasound examination was the muscularis propria. Nine cats had enlarged abdominal lymph nodes, and seven were due to metastatic disease. Metastatic disease was not routinely detected by ultrasound in the liver (1/4 cats) or the spleen (0/3 cats). Concurrent small cell (T cell) lymphoma was present in four of 14 cats (29%).