A. Stout, F. Constantino-Casas, C. Partington
Background
Cardiac neoplasia in cats is uncommon, with lymphoma being the most frequently reported type. Cardiac lymphoma may occur as primary or secondary disease, with secondary dissemination being more common. Clinical manifestations depend on the location and extent of infiltration, which can result in effusions, obstruction, and myocardial dysfunction. This report describes an unusual case where lymphoma infiltrated the pulmonary valve, causing severe pulmonary stenosis and right-sided congestive heart failure.
Methods
A nine-year-old neutered male domestic shorthair cat was referred for investigation of a suspected renal mass with clinical signs of polyuria, polydipsia, weight loss, and later respiratory effort. Echocardiography and thoracocentesis were performed, followed by postmortem and histopathological evaluation after sudden death during hospitalization.
Results
Echocardiography revealed a large homogenous mass within the right ventricular outflow tract, infiltrating the pulmonary valve leaflets and causing severe infundibular and valvular pulmonary stenosis, with secondary right atrial and ventricular dilation. Postmortem confirmed pulmonary valve infiltration, myocardial involvement, and disseminated lymphoma affecting multiple organs, including the kidney, pancreas, diaphragm, and adrenal glands. Histopathology confirmed intermediate to large cell lymphoma. The cat’s condition progressed rapidly, with sudden death occurring within hours of presentation.
Limitations
Cytology of the pleural effusion was not performed, as the owner declined further diagnostics. No electrocardiogram was recorded, so arrhythmia as a potential cause of sudden death could not be confirmed. The inability to determine the primary site of the lymphoma was another limitation.
Conclusions
This case highlights a rare manifestation of cardiac lymphoma in cats, with unique infiltration of the pulmonary valve leading to severe pulmonary stenosis and right-sided heart failure. The report emphasizes the need to consider lymphoma as a differential diagnosis for any feline cardiac mass, regardless of location. Prognosis for cardiac lymphoma remains poor, though rare cases of remission with chemotherapy have been reported.
Right parasternal short-axis view at the heart base. (A) Two-dimensional echocardiography showing an extensive, homogenous, obstructive mass (arrow) within the right ventricular outflow tract at the level of the pulmonary valve leaflets (appearing to invade the leaflets) and infundibulum and extending to and infiltrating the right ventricular free wall. The right atrium is severely dilated, and there is a large volume of pleural effusion. (B) Colour flow Doppler showing turbulent blood flow within the right ventricular outflow tract and pulmonary artery as a result of the obstructive lesion. (C) Continuous wave spectral Doppler of the pulmonary artery flow, showing increased flow velocity across the area of obstruction (as a result of reduced right ventricular systolic function, the transpulmonic velocity underestimated the severity of obstruction). Ao: aorta; PA: pulmonary artery; PLE: pleural effusion; RA: right atrium; RVOT: right ventricular outflow tract.
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