Cerebral angioendotheliomatosis in a dog

Recurrent cerebrovascular accidents caused by intravascular lymphoma in a dog

An eight-year-old, neutered male labrador was presented with recent recurrent vestibular episodes. MRI was consistent with multiple lacunar ischaemic infarcts in the thalamus and medulla oblongata. The imaging diagnosis was supported by a markedly elevated D-dimer concentration. Despite a comprehensive diagnostic workup (including fine needle cytology of cutaneous and subcutaneous nodules, complete bloodwork, urinalysis, thoracic and abdominal imaging, cerebrospinal fluid analysis, serial blood pressure measurements, echocardiography, electrocardiography and brainstem auditory evoked response testing), no underlying cause was found. After a partial response to 2  mg/kg clopidogrel once a day and 1  mg/kg prednisolone once a day, the dog acutely deteriorated and repeated MRI of the brain revealed an intra-axial haemorrhagic mass. Euthanasia was elected and postmortem examination revealed the presence of an intravascular null-cell lymphoma, exclusively in the central nervous system. Intravascular lymphoma is rare, difficult to diagnose ante-mortem and reports in veterinary literature are few.

Canine intravascular lymphoma with overt leukemia

A 6-year-old spayed Labrador Retriever Mix dog was evaluated for a 2-week history of progressive generalized weakness and reluctance to stand. Physical examination revealed severe weakness with obtunded mentation, head tilt, bilateral nystagmus, and decreased vision. CBC findings included mild nonregenerative anemia, marked thrombocytopenia, and a few atypical mononuclear cells on the blood film. The cells were 15-30 μm in diameter and had round to oval to reniform centrally placed nuclei with stippled chromatin, prominent nucleoli, and abundant basophilic cytoplasm with numerous discrete vacuoles and, occasionally, small azurophilic granules. Similar cells were found in bone marrow. On histologic examination of tissues collected at necropsy, neoplastic cells were detected in bone marrow, hepatic sinusoids, cerebral and meningeal vessels, and in capillaries of the heart, renal interstitium, small intestinal submucosa, and muscularis, and alveolar septa. A small discrete mass in the right atrium consisted of similar neoplastic cells, and the spleen was diffusely infiltrated. Tissue distribution was suggestive of intravascular lymphoma. Neoplastic cells in tissue sections were immunoreactive for vimentin, CD18, CD45, and granzyme B and lacked immunoreactivity for cytokeratin. Neoplastic cells on bone marrow aspirate smears and blood films lacked immunoreactivity for CD3, CD79a, CD1c, CD11b, CD11c, CD11d, and E-cadherin. In the absence of immunophenotypic evidence for the neoplastic cells being derived from B-cell, T-cell, or histocytic/dendritic lineages and the lack of clonal antigen receptor gene rearrangement(s), along with positive immunoreactivity for granzyme B, a tumor of NK cells was considered likely. Based on current knowledge, this is the first report of canine intravascular lymphoma, of probable NK cell origin, with peripheral blood involvement.

Cerebrovascular disease in dogs and cats

Cerebrovascular disease is defined as any abnormality of the brain resulting from a pathologic process affecting its blood supply. Stroke or cerebrovascular accident (CVA) is the most common clinical manifestation of cerebrovascular disease, and can be broadly divided into ischemic stroke and hemorrhagic stroke. Ischemic stroke results from occlusion of a cerebral blood vessel by a thrombus or embolism, depriving the brain of oxygen and glucose, whereas hemorrhagic stroke results from rupture of a blood vessel wall within the brain parenchyma or subarachnoid space. Previously considered uncommon, CVA is being recognized with greater frequency in veterinary medicine since magnetic resonance imaging has become more readily available. Once the diagnosis of ischemic or hemorrhagic stroke is confirmed, potential underlying causes should be sought after and treated accordingly.

Primary cerebral hemangiosarcoma in a 6-week-old dog

A primary cerebral hemangiosarcoma was identified in a 6-week-old, female, cross-breed dog. Grossly, the tumor mass was poorly demarcated from the adjacent neuropil, hemorrhagic, and caused effacement of the right dorsolateral cerebral hemisphere. Microscopically, the tumor was composed of an infiltrative mass of small vascular channels lined by neoplastic endothelial cells that stained variably with factor VIII-related antigen and negatively with glial fibrillary acidic protein. This is the first description of a primary intracranial hemangiosarcoma in an immature dog.

Angiotrophic intravascular lymphosarcoma presenting as bi-cavity effusion in a dog

A 9-year-old German Shepherd cross was presented with a history of dyspnoea, decreased activity, episodic collapse and abdominal distention. Cytological examination of thoracic and abdominal fluid demonstrated neoplastic cells, either round or mesenchymal in nature. The dog was found to have a mass in the heart-base region. Exploratory thoracotomy was performed to identify the exact nature of the mass histologically, and to determine if it was the source of neoplastic cells seen in the effusions. Histological diagnosis of the mass was mesothelioma. Postoperatively the dog developed thrombocytopenia, probably immune-mediated, which was treated with prednisone therapy. The dog developed signs of respiratory distress shortly before discharge and, due to its deteriorating condition, was euthanased. A necropsy was performed and tissues were collected for histological examination. The histological diagnosis was angiotropic intravascular lymphosarcoma. Diagnosis of mesothelioma was not confirmed.

Intravascular lymphoma involving the central and peripheral nervous systems in a dog

A 5-year-old, castrated male mixed-breed dog was presented for paraparesis, ataxia, hyperesthesia, and thrombocytopenia of 5 months' duration and recurrent seizures during the preceding 2 weeks. Multifocal neurological, ophthalmological, pulmonary, and cardiac diseases were identified. Magnetic resonance imaging and cerebrospinal fluid analysis supported a tentative diagnosis of neoplastic or inflammatory disease. A computed tomography-guided biopsy provided both cytopathological and histopathological evidence of intravascular lymphoma. The disease progressed despite chemotherapy with prednisone, L-asparginase, and vincristine. Postmortem histopathological examinations suggested intravascular lymphoma in the central and peripheral nervous systems as well as in multiple other organ systems. This is the first description of an antemortem diagnosis and treatment of intravascular lymphoma involving the central nervous system of a dog.

Clinicopathological and immunophenotypical features of canine intravascular lymphoma (malignant angioendotheliomatosis)

Intravascular lymphoma (IVL) is a rare angiotropic large-cell lymphoma in which neoplastic lymphocytes proliferate within the lumina of blood vessels in the absence of a primary extravascular mass or leukaemia. A retrospective review of veterinary medical records identified 17 cases of canine IVL. Spinal cord ataxia (seven dogs), posterior paralysis (one dog), seizures (four dogs) and vestibular disease (three dogs) dominated the clinical presentation. Haemorrhage, ischaemia, and occasional foci of vascular proliferation were found in tissue sections from affected dogs. Vessels, predominantly veins, throughout the body were frequently filled with neoplastic lymphocytes. Splenic involvement occurred in only one of 10 cases examined and bone marrow involvement was absent in four cases examined. Formalin-fixed paraffin wax-embedded tissues from 15 cases were examined immunohistochemically with streptavidin-biotin-horseradish peroxidase and a catalysed signal amplification system. The neoplastic cells were classified in eight cases as T cells (CD3+/IgG-/CD79a-), in one case as B cells (CD3-/CD79a.dim/IgG+), and in the remaining six cases as non-T, non-B (CD3-/IgG-/CD79a-). The clinical and pathological features of canine IVL closely resembled those of the human disease. In striking contrast to human cases, which are most often B-cell lymphomas, the immunophenotypes of the canine IVLs in this series were heterogeneous. The canine IVLs were derived primarily from T cells and non-T, non-B lymphocytes, B cells being found in only a single instance.

MR imaging findings in a dog with intravascular lymphoma in the brain

Intravascular lymphoma (malignant angioendotheliomatosis, angiotrophic lymphoma) is a rare neoplastic disorder in dogs. The literature contains few reports in dogs and a single report in a cat. Intravascular lymphoma is characterized by an intravascular proliferation of malignant lymphocytes. This unique angiocentric distribution of neoplastic cells leads to the characteristic clinicopathologic feature of thromboses and infarctions. In people, intravascular lymphoma has a predilection for vessels in the central nervous system (CNS) and skin. Typically, affected patients have episodic symptoms that coincide with the timing of infarctions. This report details the clinicopathologic description and magnetic resonance (MR) images of a dog with intravascular lymphoma that resulted in multiple CNS infarctions. Abnormalities identified with MR imaging consisted of multifocal hyperintensities observed in pre-contrast T1-weighted, T2-weighted, intermediate-weighted, and FLAIR pulse sequences. Lesions were most conspicuous on the FLAIR images. In addition, there was mild enhancement of the lesions seen in post-contrast T1 weighted images.

Primary T-cell lymphoma of the central nervous system in a dog

Primary T-cell lymphoma is a rare form of CNS neoplasia. Diagnosis may be aided by use of cytologic examination of CSF. Primary CNS T-cell lymphoma should be considered in a patient with multiple cranial nerve abnormalities, even if results of imaging studies are considered normal.

Intravascular malignant T-cell lymphoma (malignant angioendotheliomatosis) in a cat

A 7-year-old spayed female Siamese cat was presented with a 7-day history of ataxia, circling to the right, and involuntary micturition and defecation. Cerebrospinal fluid analysis showed increased protein content and relative eosinophilia. At necropsy, there was flattening of the cerebral cortical gyri of the right frontal and parietal lobes, and both kidneys had multiple wedge-shaped cortical indentations. Histologically, the cerebral cortex contained several extensive malacic foci, and the kidneys had multifocal parenchymal degeneration and atrophy. There was multifocal partial to complete thrombosis of renal interlobar arteries and of the right middle cerebral artery and meningeal branches; these thrombi contained large anaplastic round cells, which often invaded the arterial wall. Many smaller vessels within the kidneys and brain were occluded with clusters of similar cells, without thrombosis or vascular wall invasion. The neoplastic round cells had immunohistochemical staining properties of T lymphocytes.

A novel intradural extramedullary spinal cord tumor in young dogs

We have studied an unusual, spontaneous, intradural extramedullary spinal cord tumor in 12 dogs. Animals presented with paraparesis and ataxia early in life (11/12 ranged from 6 to 38 months of age) suggesting that these tumors may be congenital. Various breeds of dogs were represented with four cases in German Shepherds and three in retrievers; there was no sex predisposition. Post-mortem examinations revealed a single intradural mass consistently located between T10 and L2, which produced extensive compression of the spinal cord. Metastasis was never observed and significant pathological changes in other organs were lacking. Microscopic examination revealed solid sheets of ovoid to fusiform cells interspersed with areas of acinar and tubular differentiation. Some areas were rarified and focal squamous metaplasia was observed. Ultrastructural features included the presence of a continuous basal lamina, junctional complexes, microvilli and occasional cilia at the apices of acinar complexes. Immunocytochemical studies did not support a neurectodermal origin. At least 13 case reports of this entity have been previously published and have been designated ependymomas, medulloepitheliomas and neuroepitheliomas. A recent case was diagnosed as a nephroblastoma and we feel that this is an interesting and provocative diagnosis. These tumors could result from remnants of renal primordium which becomes trapped between the dura and the developing spinal cord. However, firm evidence of such a histogenesis is not yet at hand.

Immunohistochemistry of so called "neoplastic angioendotheliosis"

Three cases of "neoplastic angioendotheliosis" were examined immunohistochemically by the peroxidase-antiperoxidase method for Factor VIII-related antigen and various leukocyte markers. In all three cases, the tumor cells stained positively for common leukocyte antigen. IgM, and kappa or lambda light chains were demonstrable in two cases. Stains for carcino-embryonic antigen and muramidase were negative. This indicates that the neoplastic cells in the lumen of blood vessels were of lymphoid origin.