Diffuse Pulmonary Adenocarcinoma with Micropapillary Growth Pattern in a Cat.

A 12-year-old female European shorthair cat was presented with severe dyspnoea. Echocardiography revealed hypertrophic cardiomyopathy and pleural effusion. The cat died from acute decompensated left heart failure. At necropsy examination, the lungs were diffusely congested and firm, with multifocal grey areas and sparse haemorrhages. No solid masses were detected. Histopathology revealed a diffuse neoplastic proliferation characterized by irregular growth along alveolar walls with a micropapillary pattern. Tumour cells were large, highly pleomorphic and intensely positive for pan-cytokeratin and CAM 5.2. Tumour growth was obscured by simultaneous lesions related to chronic pulmonary congestion and interstitial lung disease. Histological features were consistent with a diffuse invasive pulmonary adenocarcinoma with a micropapillary pattern of tumour growth. Differential diagnosis included large cell carcinoma, which is usually characterized by rosettes or solid clusters of cells occupying alveolar lumen. Extensive cytokeratin immunolabelling was helpful in the differentiation from histiocytic proliferative disease.

Unexpected Cardiac Death During Anaesthesia of a Young Rabbit Associated with Fibro-fatty Replacement of the Right Ventricular Myocardium.

A 6-month-old female pet rabbit was presented for routine ovariectomy. The pre-anaesthetic evaluation was unremarkable and no anaesthetic complications occurred during the procedure. However, at the end of the surgery, the rabbit suddenly showed acute bradycardia and cardiac death. Necropsy examination revealed marked dilation of the right ventricle, associated with diffuse thinning of the right ventricular free wall. Gross and histopathological findings were suggestive of a congenital dilated cardiomyopathy characterized by fibro-fatty replacement of the right ventricular myocardium. Similar myocardial lesions have not been previously described in rabbits, although they have been documented in myocardial diseases of man, dogs, cats, cattle, horses and chimpanzees.