Association between ultrasonographic appearance of splenic parenchyma and cytology in cats

Objectives: The purpose of this study was to determine whether the presence of a splenic mass or a diffusely moth-eaten parenchyma on ultrasonographic scans could represent potential criteria of malignancy in the feline spleen. Methods: Feline patients with ultrasonographic images and cytological analysis of the spleen obtained by fine-needle aspiration were retrospectively included in a multicentre study. Results: One hundred and ninety-five cats met our inclusion criteria. There was a lack of agreement between the moth-eaten ultrasonographic appearance of the spleen and the presence of a malignant neoplasia on cytological analysis. The sensitivity and specificity of a moth-eaten parenchyma for predicting malignant neoplastic disease were 13.2% and 84.8%, respectively. The sensitivity and specificity of a splenic mass >1 cm for predicting malignant neoplastic disease were 21.0% and 94.7%, respectively. A marbled appearance of the splenic parenchyma was significantly more frequent among patients examined with a high-frequency transducer (11–18 MHz) than among those examined with a low-frequency transducer (6.6–10 MHz) (27.6% vs 11.1%, respectively; P = 0.004). Similarly, although not statistically significant, a moth-eaten parenchyma was more frequent in the high-frequency transducer group than in the low-frequency group (17.1% vs 8.9%, respectively; P = 0.09). Conclusions and relevance: Based on our findings, a moth-eaten ultrasonographic appearance of the spleen in cats does not necessarily reflect a lymphoma or another malignant neoplastic process on cytological analysis. The presence of a splenic mass >1 cm on ultrasound is suggestive of malignancy in cats. Finally, the transducer frequency must be taken into account when assessing the splenic parenchyma, as a high-frequency transducer seems to improve the detection of a marbled or moth-eaten parenchyma.