History

An adult 2.02-kg female backyard domestic chicken (Gallus gallus domesticus) of unknown age was submitted for postmortem examination. The chicken had suddenly become recumbent and had died within a 30-minute period thereafter.

Gross Findings

At necropsy, the chicken was overweight as evidenced by abundant intracoelomic adipose tissue. The surface of the liver was diffusely covered with a thick layer of dark-red coagulated blood (Figure 1), which was adhered to the underlying capsule by thin, stringy, brown to tan fibrinous exudate. The liver was diffusely pale tan and enlarged (approx 1.5 times the size of a typical healthy adult chicken's liver) and contained multifocal, raised, round to irregularly shaped (maximum dimension, 1 to 5 mm), red or dark-red nodules. On cut surface, the nodules extended into the underlying parenchyma and were well demarcated from the adjacent hepatic parenchyma. The caudolateral aspect of the left liver lobe contained a 3.5 X 2.5 X 2.5-cm cystic structure with a dark-brown to black capsule that was filled with dark-red fluid (subcapsular hemorrhage). The spleen had a slightly raised, 1.5-mm-diameter, red to dark-red nodule. No other notable gross findings were observed.

View Full Size

Photographs of the liver and abundant coelomic fat in an adult female chicken (Gallus gallus domesticus) that died within 30 minutes after suddenly becoming recumbent. A—A thick layer of blood clots covering the entire liver is partially removed from the left hepatic lobe. B—After removal of the blood clots on the capsular surface, the liver is diffusely pale tan with numerous, raised, dark-red nodules. The left liver lobe has focally extensive subcapsular hemorrhage (asterisk).

Citation: Journal of the American Veterinary Medical Association 259, 6; 10.2460/javma.259.6.609

• Download Figure
• Download figure as PowerPoint slide

Histopathologic Findings

Selected tissues were fixed in neutral-buffered 10% formalin and processed for histologic examination. Effacing approximately 40% to 50% of the hepatic parenchyma was an unencapsulated, fairly circumscribed, moderately cellular, infiltrative neoplasm composed of variably shaped and sized lakes of blood-filled vascular spaces lined by polygonal to spindle-shaped neoplastic cells, supported by moderate amounts of fibrovascular stroma (Figure 2). Each neoplastic cell had indistinct cell borders, a mild amount of granular eosinophilic cytoplasm, and a single oval nucleus containing finely stippled chromatin and no prominent nucleoli. Anisocytosis and anisokaryosis were mild to moderate with 1 to 2 mitotic figures/10 hpf (400X). Similar neoplastic cells were observed in the lungs and accounted for approximately 20% of the pulmonary parenchyma in 1 tissue section (Figure 3). The splenic nodule was a large, partially organized hematoma that was circumferentially encased by a fibrous capsule. Additional histologic findings were not interpreted as clinically relevant to the acute decompensation and death of the chicken.

View Full Size

Photomicrographs of sections of the liver. A—The hepatic parenchyma is effaced and replaced by variably sized blood-filled spaces. H&E stain; bar = 2 mm. B—The blood-filled spaces are lined by polygonal to spindle-shaped neoplastic endothelial cells with rare mitoses (asterisk). H&E stain; bar = 100 µm.

Citation: Journal of the American Veterinary Medical Association 259, 6; 10.2460/javma.259.6.609

• Download Figure
• Download figure as PowerPoint slide

View Full Size

Photomicrograph of a section of lung tissue. Variably sized neoplastic foci have effaced and replaced the pulmonary parenchyma. H&E stain; bar = 2 mm.

Citation: Journal of the American Veterinary Medical Association 259, 6; 10.2460/javma.259.6.609

• Download Figure
• Download figure as PowerPoint slide

Molecular Diagnostic Findings

Immunohistochemical staining for factor VIII–related antigen^a was performed on formalin-fixed, paraffin-embedded (FFPE) sections of the liver, and no immunoreactivity was seen in either neoplastic or nonneoplastic endothelial cells. A frozen sample of lung tissue was tested by PCR assay with primers that targeted the genomes of avian leukosis virus (ALV) types A, B, C, D, E, and J; Rous virus; and reticuloendotheliosis virus. A positive reaction was observed only for ALV-E. Additional PCR assaying and sequencing of the ALV long terminal repeat region was performed; by use of a bioinformatic search tool,^b the sequences matched (99%) the endogenous ALV long terminal repeat region (ALV strain TW-3593 [complete genome]; GenBank HM582658.1). The genome sequence was archived as GenBank accession No. MK346999.

Morphologic Diagnosis and Case Summary

Morphologic diagnosis: hepatic hemangiosarcoma and hemocoelom with pulmonary metastasis.

Case summary: acute decompensation and death caused by disseminated hemangiosarcoma resulting in hemocoelom in a backyard chicken.

Comments

The chicken of the present report died of hypovolemic shock attributed to hemocoelom caused by rupture of a hepatic hemangiosarcoma. At necropsy, before blood clots on the liver were removed, fatty liver hemorrhagic syndrome was highly suspected because it is a more common cause of hepatic rupture and hemocoelom in hens, especially overweight birds.¹ In addition to fatty liver hemorrhagic syndrome and hepatic hemangiosarcoma, trauma should be included in the differential diagnoses for hepatic rupture in hens. Although gross lesions in the lungs of the chicken were not evident at necropsy, pulmonary metastasis of hemangiosarcoma was confirmed histologically. Grossly, the splenic mass was suspected to be part of the neoplasm; however, it was histo-logically confirmed to be a partially organized hematoma and no neoplastic cells were observed within multiple sequential tissue sections.

Visceral hemangiosarcoma is a highly malignant neoplasm of vascular endothelial origin that is associated with frequent metastasis.² The neoplasm is most frequently described in dogs, with primary involvement of the spleen, liver, right auricle of heart, and skin. There are a few reports^3–13 of hemangiosarcoma in domestic poultry and pet birds. Vascular neoplasms in the skin and visceral organs of chickens with retroviral infection have been reported, particularly in birds infected with ALV containing the erb-B oncogene, avian hemangioma virus (which had a close homology to avian leukosis Rous-associated virus-1 devoid of oncogene), and ALV subtypes A and J.^3,4,14–17 Although ALV-A and ALV-J predominantly cause lymphoid leukosis and myeloid leukosis, respectively, ALV-A– and ALV-J–associated vascular neoplasms in chickens have been reported.^4,14 In the case described in the present report, infection with ALV-E but not with ALV-A, ALV-J, or the other ALV subtypes was detected by PCR assay. Subtype E is an endogenous ALV and generally considered marginally oncogenic or nononcogenic because the long terminal repeat region has weak gene promoter activity.^4,16 Therefore, the hemangiosarcoma in the chicken of the present report was considered a spontaneous nonviral-associated neoplasm.

For diagnosis of hemangiosarcomas in most cases, immunohistochemical analysis is not necessary, although it can be helpful to confirm poorly differentiated hemangiosarcomas. Antibodies against factor VIII (von Willebrand factor)–related antigen are known to work well on FFPE histologic sections obtained from dogs, and anti-CD31/platelet endothelial cell adhesion molecule (PECAM) antibodies are often used to immunolabel endothelial-derived cells.¹⁸ Immunoreactivity for factor VIII–related antigen in neoplastic endothelial cells in avian species has been reported.^9,10,12 In the case described in the present report, immunohistochemical staining for factor VIII–related antigen was performed on FFPE histo-logic sections, and no immunoreactivity was seen in either neoplastic or nonneoplastic endothelial cells. This finding suggested that the particular antibody used is not of diagnostic merit for immunolabeling endothelium on FFPE histologic sections or for the immunostaining method we used (antigen retrieval) with regard to tissues of domestic chickens.

Treatment options for hemangiosarcoma include surgical excision combined with radiation therapy, chemotherapy, or both. Reported treatments in avian species include surgical excision alone and radiation therapy.^5,11 A budgerigar with carpal hemangiosarcoma was treated with local irradiation of the wing 3 times weekly for a total of 10,400-cGy fractions, which resulted in remission for 4 weeks; however, the neoplasm recurred, and disseminated metastasis involving the skin, lungs, right atrial myocardium, liver, vertebrae, crop, and cloaca was confirmed during postmortem examination.⁵

For the chicken of the present report, acute recumbency and death was attributed to rupture of the hepatic hemangiosarcoma resulting in hemocoelom and hypovolemic shock. The liver was presumed to be the primary site of the hemangiosarcoma, with intrahepatic metastasis and pulmonary metastasis. Although hemangiosarcoma is uncommon in avian species, rupture of a visceral hemangiosarcoma should be considered a potential cause of intracoelomic hemorrhage. Because the hemocoelom was caused by a neoplasm in this case, there was low likelihood of other hens in the flock being affected. If the hemocoelom had been caused by obesity and a ruptured fatty liver, it might have been beneficial to recommend modification of the flock's diet to reduce the risk of death among the other hens.¹