Splenic extramedullary hematopoiesis in dogs is frequently detected on multiphase multidetector‐row CT as hypervascular nodules

Abstract

Extramedullary hematopoiesis (EMH) is the formation and development of blood cells outside the bone marrow, and in dogs it frequently occurs in the spleen. Although splenic EMH is a relatively common condition, data regarding its appearance in veterinary medicine are lacking. Our aim was to describe different multidetector computed tomographic (MDCT) features of splenic EMH in dogs. In this descriptive retrospective study, dogs with cytological diagnosis of splenic EMH and three‐phase MDCT study of the abdomen were included. Multi‐detector CT findings recorded were splenomegaly, appearance of the parenchyma, and mean attenuation of the spleen and lesions. Out of 89 dogs included, 55 (62%) presented multifocal nodular aspect, 14 (16%) mass, 12 (13%) diffuse heterogeneous parenchyma, and eight (9%) normal spleen. Most lesions were hyperattenuating to the parenchyma in the arterial (57/89, 64%) and portal (59/89, 66%) phases; whereas in the interstitial phase only 40 of 89 (45%) were hyperattenuating. The mean attenuations of the lesions were higher compared to the values of the adjacent spleen, and the difference of the mean attenuation between the hyperattenuating lesions and the parenchyma was significantly higher in arterial and portal phases than in interstitial phase (P < .0001). The most frequent MDCT aspect of splenic extramedullary hematopoiesis consists of multiple nodules hyperattenuating to the normal spleen, best visualized in the arterial and portal phases.

Comparison between computed tomographic and ultrasonographic findings of the liver and spleen in dogs with confirmed hepatic or splenic lymphoma involvement

“…This is likely to be the case of the dog with a splenic lymphoma that has a single splenic nodule visible only on CT and a generally heterogenous splenic parenchyma on US (Figure 3). This nodule was hyperattenuating on CT post‐contrast and therefore likely to represent extramedullary haematopoiesis according to a recent publication 17 . However, there is no cytological confirmation of the nature of this nodule.…”

“…This finding must be interpreted carefully and is likely to be related to the low number of livers and spleens without lymphoma in our study. The presence of splenic or hepatic nodules or masses is a common and non‐specific finding in both modalities with a wide range of differential diagnoses including nodular hyperplasia, extramedullary haematopoiesis, primary or metastatic neoplasia, haematoma or infection 10,11,15–17 . Additionally, it is also possible that a patient could have lymphoma infiltration of the organ and a non‐neoplastic nodule.…”

A Machine Learning-Based Approach for Classification of Focal Splenic Lesions Based on Their CT Features

“…Haematomas are reported as mainly heterogeneously enhancing masses in all phases by both Kutara et al ( 2 ) and Jones et al ( 7 ). Splenic extramedullary haematopoiesis nodules have been described as having a very variable appearance and as hyperenhancing in all phases ( 4 ). The CT features of all the other possible OBLs (e.g., splenitis, lipoma, etc.)…”

“…Despite FSLs being a common finding in canine ultrasound (US) and computed tomography (CT) ( 4 ) there is a general paucity of studies systematically describing their imaging features. No specific US features are reported as useful in distinguishing between different FSL histotypes ( 5 ).…”

Atypical Lesions in Canine Leishmaniosis: Description of New Cases

“…Benign lesions correspond mainly to nodular hyperplasia, which can be purely lymphoid or complex hematomas, hemangiomas, and extramedullary hematopoiesis. Malignant lesions are mainly hemangiosarcoma, histiocytic sarcoma, lymphomas, or other sarcomas [ 4 , 43 , 44 , 45 ]. Due to this large number of differential diagnoses of splenic lesions in dogs, a microscopic study is always recommended in dogs infected with Leishmania , especially in natural cases in which other infections may coexist, such as some hemoparasites or protozoa that can induce splenomegaly and lymphoid hyperplasia [ 43 ].…”