Two haemangioendotheliomas in a bovine brain

A Review of Proliferative Vascular Disorders of the Central Nervous System of Animals

In disease, blood vessel proliferation has many salient roles including in inflammation, when granulation tissue fills superficial defects, or in the recanalization of an occluded blood vessel. Sometimes angiogenesis goes awry-granulation can be exuberant, and plexiform proliferation of vascular components can contribute to pulmonary hypertension. This review focuses on the diverse manifestations of pathologic vascular overgrowth that occur in the brain, spinal cord, and meninges of animals from birth until old age. Entities discussed include systemic reactive angioendotheliomatosis in which glomeruloid vascular proliferations are encountered in various organs including the central nervous system (CNS). The triad of CNS vascular malformations, hamartomas, and benign vascular proliferations are an especially fraught category in which terminology overlap and the microscopic similarity of various disorders makes diagnostic classification incredibly challenging. Pathologists commonly take refuge in "CNS vascular hamartoma" despite the lack of any unique histopathologic features and we recommend that this diagnostic category be abandoned. Malformative lesions that are often confusing and have similar features; the conditions include arteriovenous malformation, cavernous angioma, venous angioma, and capillary telangiectases. Meningioangiomatosis, a benign meningovascular proliferation with dual components, is a unique entity seen most commonly in young dogs. Last, accepted neoplastic conditions range from lower-grade locally acquired growths like hemangioblastoma (a tumor of mysterious interstitial stromal cells encountered in the setting of abundant capillary vasculature proliferation), the rare hemangioendothelioma, and the highly malignant and invariably multifocal metastatic hemangiosarcoma. Additionally, this review draws on the comparative medical literature for further insights into this problematic topic in pathology.

Epithelioid Variant of Hemangioma and Hemangiosarcoma in the Dog, Horse, and Cow

Epithelioid hemangiomas, hemangioendotheliomas, and angiosarcomas are well recognized histologic variants of endothelial tumors in humans that in the past have been confused with neoplasms of epithelial or histiocytic origin. We describe 12 epithelioid endothelial vascular tumors in 8 dogs, 3 horses, and 1 cow that share microscopic features with these tumors in humans. Ten tumors were located within the dermis and subcutis, 1 in the gastrocnemius tendon, and 1 in the skeletal muscle of the thigh. Key histologic features were the plump, epithelioid appearance of neoplastic endothelial cells and occasional cytoplasmic vacuolation, which rarely contained a single erythrocyte. Patterns of epithelioid endothelial cell growth ranged from conventional vasoformative structures to glandlike acini and short ducts to solid, sheetlike arrangements. All tumors were positive for endothelial markers: 12/12 (100%) were positive for von Willebrand factor with variable intensity and distribution and 9/9 (100%) were positive for CD31. All 12 were negative for cytokeratin. We subdivided these tumors into epithelioid hemangiomas (n = 3) and hemangiosarcomas (n = 9) based on conventional morphologic criteria, growth pattern (invasive or not), and metastasis (known in 1 case at the time of biopsy). Additional follow-up information obtained by a written questionnaire was available for 6/12 (50%) animals and revealed local recurrence in 3 animals (1 epithelioid hemangioma and 2 epithelioid hemangiosarcoma) and regional metastasis in 3 animals (all epithelioid hemangiosarcomas). This series represents a novel group of vascular tumors in domestic animals of which there are only 3 previous cases reported in the veterinary literature.

Epithelioid hemangiosarcomas of the bovine urinary bladder: a histologic, immunohistochemical, and ultrastructural examination of four tumors

Epithelioid hemangiosarcoma is a specific variant of hemangiosarcoma that has recently been recognized in domestic animals. These malignant vascular neoplasms histologically resemble, and may be mistaken for, carcinomas. Four epithelioid hemangiosarcomas in the urinary bladders of 4 cows with severe enzootic hematuria are described in the current study. Grossly, the vesicular mucosa of the urinary bladder of each cow contained a single red elevated nodule. Histologically, each neoplasm was composed of short strands, cords, or nests of epithelioid, round, or slightly spindle-shaped endothelial cells that formed small vascular structures. Neoplastic cells were immunohistochemically positive for factor VIII-related antigen and vimentin, and were negative for cytokeratin and desmin. Ultrastructurally, the neoplastic cells often contained cytoplasmic intermediate filaments, a prominent granular endoplasmic reticulum, a Golgi complex, mitochondria, marked pinocytotic activity, and rare Weibel-Palade bodies. These neoplasms were diagnosed as epithelioid hemangiosarcomas based on their histologic, immunohistochemical, and ultrastructural features. The present report widens the spectrum of mesenchymal tumors of the bovine urinary bladder and aids in the characterization of these vascular neoplasms.

Immunohistochemical Evaluation of Vascular Urinary Bladder Tumors from Cows with Enzootic Hematuria

Fifty-six endothelial-derived urinary bladder tumor samples collected from 26 animals with bovine enzootic hematuria were selected for immunohistochemical studies. Expression of factor VHI-related antigen (FVIIIra), CD31, muscle-specific actin, uroplakin III (UPIII), and the cell cycle-related proteins cyclin Dl and p53 was evaluated in hemangiomas, “hemangioendotheliomas” (a vascular tumor that histologically is intermediate in appearance between a hemangioma and a conventional hemangiosarcoma), and hemangiosarcomas. Although CD31 expression was seen in all endothelial tumors tested, FVIIIra was not expressed in poorly differentiated endothelial tumor cells from solid areas or in 7 muscle-invasive hemangiosarcomas. Cyclin Dl overexpression was seen in 53% of hemangiomas, 82% of hemangioendotheliomas, and 95% of hemangiosarcomas. P53 immunoreac-tivity was only seen in muscle-invasive hemangiosarcomas. The UPIII staining pattern, normally very intense on the apical aspect and cytoplasm of superficial urothelial cells, was altered in the urothelium in an estimated 25% of hemangiomas, most hemangioendotheliomas, and most hemangiosarcomas. In conclusion, CD31 is a better marker than FVIIIra in the characterization of bovine endothelial tumors. The cell cycle regulatory pathways involving cyclin Dl and p53 seem to be impaired in endothelial urinary bladder tumors, p53 immunoreactivity positively correlating with enhanced invasion.

Haemangiopericytoma in a calf

After castration, a Japanese Black male calf developed subcutaneous tumours near the scrotum. They were surgically excised, and no recurrence was detected two years after surgery. The tumours were characterised by neoplastic cells concentrically arranged around blood vessels of various sizes. The neoplastic cells contained many cytofilaments, and the majority of the cells expressed smooth muscle actin, but focal densities were not found. On the basis of the immunohistochemical and ultrastructural features, the tumours were considered to be of pericyte origin.