Concurrent renal amyloidosis and thymoma resulting in a fatal ventricular thrombus in a dog

Acute and chronic systemic inflammation associated with canine nodular splenic lesions composed of heterogeneous cell components: four cases (2020-2024)

OBJECTIVES

To describe the clinical presentation and clinicopathological findings of dogs with nodular splenic lesions composed of heterogeneous cell components associated with systemic inflammation and to provide information on the outcome after surgical resection.

MATERIALS AND METHODS

Medical records were searched for dogs with histologically and immunohistochemically characterised nodular splenic lesions with mixed stromal, histiocytic and lymphoid cells and the presence of systemic inflammatory markers at the time of diagnosis.

RESULTS

Four dogs were included, of which three had an undifferentiated splenic stromal sarcoma and one had a splenic leiomyosarcoma. Fever and abdominal pain were reported in three and four cases, respectively. All dogs showed hyperglobulinaemia and marked changes in the serum protein electrophoresis profile. C-reactive protein and fibrinogen concentrations were both increased in three cases. These abnormalities completely resolved after splenectomy. Moreover, two dogs had concomitant glomerular disease and one dog had liver amyloidosis. Three dogs were still alive and asymptomatic 1, 6 and 9 months after surgery. One dog died 16 months after the initial presentation due to complications related to progressive renal failure.

CLINICAL SIGNIFICANCE

Based on this report, nodular splenic lesions with heterogeneous cell components may directly be associated with a pro-inflammatory state and should be considered as part of the differential diagnosis of fever and hyperglobulinaemia in dogs. Furthermore, early recognition and treatment of these lesions could reduce the risk of systemic complications potentially associated with amyloid deposit and organ failure.

Concurrent renal amyloidosis and thymoma resulting in a fatal ventricular thrombus in a dog

Thymoma-associated nephropathies have been reported in people but not in dogs. In this report, we describe a dog with thymoma and concurrent renal amyloidosis. A 7-year-old castrated male Weimaraner was presented for progressive anorexia, lethargy, and tachypnea. The dog was diagnosed with azotemia, marked proteinuria, and a thymoma that was surgically removed. Postoperatively, the dog developed a large left ventricular thrombus and was euthanized. Necropsy confirmed the presence of a left ventricular thrombus and histopathology revealed renal amyloidosis. We speculate that the renal amyloidosis occurred secondary to the thymoma, with amyloidosis in turn leading to nephrotic syndrome, hypercoagulability, and ventricular thrombosis. This case illustrates the potential for thymoma-associated nephropathies to occur in dogs and that dogs suspected to have thymoma should have a urinalysis and urine protein creatinine ratio performed as part of the pre-surgical database.