Ultrasonographic findings of feline large intestinal adenocarcinoma and high-grade lymphoma.

ObjectivesThe aim of this retrospective study was to describe the ultrasonographic findings of cats with large intestinal adenocarcinoma (ACA) and high-grade lymphoma (LSA).MethodsCats diagnosed with large intestinal neoplasia with a complete abdominal ultrasound were included in the study. Signalment, clinical history, physical examination, blood work and outcome data were collected. Tumor location, length, wall thickness and layering, echogenicity, lymphadenopathy, effusion, ulceration and obstruction were recorded.ResultsA total of 44 cats had ACA, with the colon affected in 28/44 cats and the ileocolic junction (ICJ) affected in 16/44 cats. The ACA tumors had a median length of 23 mm and a median wall thickening of 9 mm. Regional lymphadenopathy was noted in 29/44 cats, with a median thickness of 6.05 mm. Obstruction was observed in 30% of the cats with ACA. In total, 38 cats were diagnosed with high-grade LSA, primarily affecting the ICJ in 20/38 cats, the colon in 14/38 cats and multiple sites within the gastrointestinal tract in 4/38 cats. In addition, 7/38 cats had other organ involvement. The LSA tumors had a median length of 40.3 mm and a median wall thickening of 15 mm. Regional lymphadenopathy was noted in 31/38 cats, with a median thickness of 8.6 mm. Obstruction was present in 11% of the cats with LSA. Both tumor types commonly appeared as transmural hypoechoic thickening with loss of wall layering. The median survival time for cats with large intestinal ACA and LSA was 19 days and 23 days, respectively.Conclusions and relevanceCats with large intestinal ACA and LSA shared a similar clinical presentation. ACA and LSA share similar ultrasonographic features; however, LSA lesions are typically thicker and longer and are associated with more frequent and pronounced lymphadenopathy than ACA lesions. ACAs are more likely to cause obstruction, whereas LSA tumors tend to have a multicentric distribution. Because imaging findings overlap, cytologic or histologic sampling remains essential for definitive diagnosis.