Intra-atrial rhabdomyoma causing chylopericardium and right-sided congestive heart failure in a dog

Ultrasound, Histomorphologic, and Immunohistochemical Analysis of a Cardiac Tumor with Increased Purkinje Cells Detected in a Canine Fetus 42 Days into Pregnancy

A seven-year-old healthy female Chow Chow was referred for pregnancy monitoring. Ultrasonography was used to evaluate all pregnancy and fetus parameters, and they were found to be normal. During the examination of the 42 day pregnant bitch, an unusual mass was seen in a fetus's heart. This fetus had a cardiac frequency of 273-300 beats, while the others had heart rates of 220-240 beats. Natural vaginal birth occurred at 63 days pregnant: the first two puppies were stillborn but perfectly formed, and the other three were alive and had optimal APGAR. In one of two deceased puppies, an unusual, reddish, smooth mass occupying the space in the heart was found through necroscopy. The organ was submitted for histological examination. Histopathology, immunohistochemical, and histochemical analyses all indicated a cardiac tumor with increased Purkinje cells. This type of tumor has been described in infants, swine, bearded seals, and deer but never in fetuses and neonates of dogs. To our knowledge, this is the first such case reported in veterinary medicine.

Pericardial Hemangiosarcoma in a 10-Year-Old Papillon

A 10 yr old papillon was evaluated for lethargy, inappetence, tachypnea, and labored breathing. Physical examination findings included dehydration, tachypnea, tachycardia, and muffled heart sounds. Thoracic radiographs revealed an enlarged cardiac silhouette. Echocardiography revealed a mild volume of pericardial effusion and no evidence of right atrial tamponade or a cardiac-associated mass. Cytological analysis of the pericardial effusion was consistent with blood. There was no evidence of neoplasia. Coagulation parameters were within normal limits. Initial treatment consisted of pericardiocentesis. A subtotal pericardiectomy was later performed. No surgical complications were noted, and the dog was discharged 2 days following surgery. Results of the histological examination of the pericardium revealed hemangiosarcoma. Treatment with doxorubicin was initiated 12 days after surgery, at which time, pulmonary metastasis was suspected. The dog survived for 18 days after subtotal pericardiectomy, when it was euthanized because of complications presumably related to pulmonary metastatic disease. This is the first published report of primary pericardial hemangiosarcoma. The dog had a short survival time; thus, the response to subtotal pericardiectomy combined with adjuvant doxorubicin treatment could not be determined. Pulmonary metastatic disease was suspected 12 days following surgery. Based on this case report, pericardial hemangiosarcoma carries a guarded prognosis.

A descriptive review of cardiac tumours in dogs and cats

Cardiac tumours are uncommon in the canine and feline population and often an incidental finding. Common types include haemangiosarcoma (HSA), aortic body tumours (chemodectoma and paraganglioma) and lymphoma. These neoplasms can cause mild to severe, life-threatening clinical signs that are independent of the histological type and may be related to altered cardiovascular function or local haemorrhage/effusion into the pericardial space. Cardiac tumours may require symptomatic treatment aimed at controlling tumour bleeding and potential arrhythmias, and other signs caused by the mass effect. Additional treatment options include surgery, chemotherapy and radiotherapy. For all medical therapies, complete remission is unlikely and medical management, beyond adjunctive chemotherapy in HSA, requires further investigation but combination chemotherapy is recommended for lymphoma. The aim of this report is to summarize and critically appraise the current literature in a descriptive review. However, interpretation is limited by the lack of definitive diagnosis and retrospective nature of most studies.

Histomorphologic and Immunohistochemical Characterization of a Cardiac Purkinjeoma in a Bearded Seal (Erignathus barbatus)

The most common cardiac tumors of heart muscle are rhabdomyomas, solitary or multiple benign tumors of striated muscle origin. While cardiac rhabdomyomas are well described in human medical literature, limited information depicting the occurrence of cardiac rhabdomyomas in veterinary species exists. A case of multiple firm white nonencapsulated nodules in the heart of a bearded seal is described. Microscopic findings included cytoplasmic vacuolization with formation of spider cells, glycogen vacuoles, and striated myofibrils. These cells expressed immunoreactivity for neuron-specific enolase and protein gene product 9.5, a marker for neuronal tissue and Purkinje fiber cells. Immunoreactivity for protein gene product 9.5 along with other microscopic findings substantiates Purkinje fiber cell origin of the cardiac rhabdomyoma in the bearded seal and use of the termpurkinjeomato describe this lesion.

A Comparative Review of Canine and Human Rhabdomyosarcoma With Emphasis on Classification and Pathogenesis

Rhabdomyosarcomas are a diverse group of malignant mesenchymal neoplasms exhibiting variable levels of differentiation toward skeletal myocytes. Neoplastic cells may resemble relatively undifferentiated myoblasts, satellite cells, or more differentiated elongated spindle cells and multicellular myotubes. In veterinary medicine, classification into subtypes and variants is based on an outdated system derived from human pathology and is solely based on histologic characteristics. In contrast, classification of human rhabdomyosarcoma is based on histologic, immunohistochemical, and molecular diagnostic techniques, and subclassification has clinical and prognostic relevance. Relevance of tumor subtyping has not been established in veterinary medicine. Recent discoveries of components of the molecular pathogenesis and genomes of human rhabdomyosarcomas have led to new diagnostic techniques and revisions of the human classification system. The current classification system in veterinary medicine is reviewed in light of these changes. Diagnosis of rhabdomyosarcoma using histopathology, electron microscopy, and the clinical aspects of human and canine rhabdomyosarcomas is compared. The clinical features and biologic behavior of canine rhabdomyosarcomas are compared with canine soft tissue sarcomas.

Canine cardiac rhabdomyoma

A well-circumscribed, expansile, and nonencapsulated cardiac rhabdomyoma composed of tightly arranged, large, variably sized, ovoid to irregular, swollen myocytes with deeply eosinophilic cytoplasm and varying degrees of cytoplasmic vacuolation was detected in an eight- to nine-month-old female beagle dog in a routine toxicology study. By histochemistry, the neoplasm was periodic acid-Schiff positive. By immunohistochemistry (IHC), neoplastic cells were positive for desmin and myoglobin and negative for vimentin and smooth muscle actin. Spontaneous lesions in the heart of young beagle dogs are rare in drug safety studies. On the basis of histopathology, histochemistry, and IHC findings, a diagnosis of cardiac rhabdomyoma was made. Cardiac rhabdomyoma is one of the most frequently occurring primary tumors of the heart and, by far, the most common neoplasm in human infants and children. To our knowledge, this is the first report of the canine cardiac rhabdomyoma.

Congestive heart failure caused by intracardiac tumours in two dogs

Congestive heart failure is a common presentation in small animal practice. Cardiac tumours are an unusual cause of congestive heart failure and, when they occur, usually cause clinical signs associated with pericardial effusion and cardiac tamponade. This case report outlines the clinical and histological findings in two dogs presented with clinical signs of congestive heart failure caused by obstruction of blood flow by intracavitary cardiac tumours. Case 1 showed signs of left-sided heart failure caused by osteosarcoma within the left atrial lumen, and case 2 presented with clinical signs of right-sided heart failure due to haemangiosarcoma occupying the right atrial and ventricular lumens. This case report provides further evidence for the inclusion of intracardiac neoplasia in the differential diagnosis for dogs with clinical signs of congestive heart failure.

Myocardial hamartoma of the right atrium in a dog

A myocardial hamartoma of the right atrium is described in an 8-year-old dog that died from pneumonia. At necropsy, a firm, mottled, dark-brown right atrial appendage, of normal shape but slightly enlarged, was found incidentally. On section, the right atrial appendage was composed of a grey-tan, solid mass. Histological features of the mass were as follows: the component cells were mature cardiac muscle cells; the mass contained all of the components of the normal heart wall (i.e., epicardium, myocardium and endocardium), but the arrangement of the component tissues was disorganized; growth of the mass was non-invasive, and continuity of the component cells with adjacent normal myocardial cells was evident, suggesting a congenital origin. This appears to be the first report of congenital myocardial hamartoma in any animal other than man.