What is your diagnosis? Muculent pleural effusion from a dog

Pleural effusion was examined from a 5-year-old, female Brittany Spaniel with a 7-day history of dyspnea, anorexia, and diarrhea. The fluid was yellow, cloudy, and slightly gelatinous, and had a total protein concentration of 2.8 g/dL, a total nucleated cell concentration of 1.1 x 10(3)/muL, and a triglyceride concentration of 177 mg/dL. A cytocentrifuged preparation contained a mixed inflammatory cell population with a predominance of small lymphocytes and abundant mucinous material in the background. The dog died 3 days later and a mass was found within the lumen and wall of the right auricle of the heart at necropsy. Histopathologic sections of the mass contained a population of anaplastic spindle cells diffusely suspended in a pale basophilic matrix, consistent with myxosarcoma. The cells were positive for vimentin and negative for cytokeratin, desmin, and von Willebrand factor VIII-related antigen. A myxoid matrix was confirmed by positive staining with Alcian blue. Myxosarcoma is a rare cardiac tumor in dogs that should be considered, along with mucus-producing carcinomas and bile, as a cause of muculent effusion.     

What is your diagnosis? Hemorrhagic effusion in a dog

Abstract: A 2‐year‐old spayed female, German Shepherd dog was presented to the University of Illinois Veterinary Teaching Hospital with a history of intermittent lethargy. On physical examination, lung sounds were increased. The dog had a mild fever (103.7°F) and mild tachycardia (120 bpm). Thoracic ultrasound revealed a sternal mass and pericardial effusion, both of which were aspirated. On cytologic examination, the pericardial fluid contained a large amount of blood and was interpreted as a hemorrhagic effusion. Nucleated cells consisted mainly of macrophages containing phagocytized RBCs and hemosiderin and many clusters of reactive mesothelial cells. The majority of mesothelial cells contained variable amounts of rod‐shaped brown pigment granules that were suspected to be iron. The granules were positive for Prussian blue and carbol–fuschin, indicative of iron potentially mixed with lipofuscin. The granules stained negatively with Melan A, rhodamine, Hall's, and periodic acid‐Schiff. The iron within the mesothelial cells was likely secondary to hemorrhage, based on the erythrophagia and accumulation of hemosiderin in macrophages. Iron deposition and phagocytic activity in mesothelial cells has been reported previously in humans and rats, but not in dogs.