CT Scans Reveal Key Differences in Heart Base Tumors in Dogs and Cats

Computed tomographic findings in canine and feline heart base tumors (25 cases)

Laura Ruiz de Alejos Blanco, Kelsey Brust, Balázs Szladovits, Randi Drees

Background

Heart base tumors (HBTs) in dogs and cats are rare but clinically significant, often presenting with nonspecific signs or being incidentally discovered. The most common types include aortic body tumors (ABTs), ectopic thyroid carcinomas (ETCs), hemangiosarcomas (HSAs), and other neuroendocrine neoplasms. Echocardiography and radiography offer limited sensitivity and specificity in identifying and differentiating these tumors. This study aimed to systematically characterize HBTs using computed tomography (CT), with particular emphasis on tumor type, location, morphology, vascularization, and potential for metastasis.

Methods

This was a retrospective, multicenter case series involving 25 animals (21 dogs, 4 cats) from two institutions between 1999 and 2022. Inclusion criteria were thoracic CT with postcontrast imaging and histologic or cytologic confirmation of an HBT. CT features were evaluated in consensus by a radiology resident and board-certified veterinary radiologist. Parameters assessed included tumor size, location, shape, margins, attenuation, enhancement, neovascularization, mass effect, invasion, effusions, and metastases.

Results

Neuroendocrine tumors (including 15 ABTs, 3 ETCs, and 3 nonspecific neuroendocrine tumors) were the most common (84%), followed by HSAs (16%). ABTs and other neuroendocrine tumors frequently resided between the aortic arch and cranial vena cava or dorsal to the pulmonary trunk, while HSAs were typically cranioventral to the aortic arch. Neuroendocrine tumors showed well-defined margins, higher postcontrast attenuation (median 110 HU), and were frequently associated with mediastinal neovascularization (76%). In contrast, HSAs had lower attenuation (median 51 HU), poorly defined margins, and were often associated with pericardial effusion (75%) and tissue invasion. Metastases (primarily pulmonary) were suspected in 36% of cases. Concurrent cranial mediastinal masses were seen in four neuroendocrine tumor cases.

Limitations

The retrospective nature, non-blinded review process, and variation in CT protocols across institutions may have introduced bias or inconsistencies. Many diagnoses were based on cytology without histologic confirmation. Pericardial effusion may have been underrepresented due to prior pericardiocentesis in some animals.

Conclusions

CT is a valuable diagnostic tool for characterizing heart base tumors in small animals, particularly in differentiating neuroendocrine tumors from hemangiosarcoma. Neuroendocrine tumors generally exhibit higher contrast enhancement and prominent neovascularization, while HSAs present more invasively with effusions. However, CT features could not reliably distinguish between ABTs and ETCs due to their similar neuroendocrine origin.

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