Vertebral Polyostotic Lymphoma in a Young Dog

Canine Oral Lymphoma: A Review and 3 Case Studies

Canine oral lymphoma is an infrequently diagnosed malignancy in dogs and reports in the literature are lacking. Most cases are due to epitheliotropic lymphoma, in which lesions are often multifocal and involve the skin as well as the oral cavity. Epitheliotropic lymphoma is an uncommon form of lymphoma that is characterized by neoplastic T-lymphocyte tropism for epithelial tissues. However, not all cases of oral lymphoma are due to epitheliotropic lymphoma, and B-cell disease is also possible. This article describes very different cases of oral lymphoma in dogs including the history at presentation, examination and radiographic findings, treatments, and outcomes. The cases highlight the variability in signalment, examination findings, and clinical courses that are found with oral lymphoma.

Case Report: Diffuse Lumbar Hyperostosis Causing Vertebral Canal Stenosis in a Dog With Concurrent Multicentric T-Cell Lymphoma

A 4-year-old female spayed Bullmastiff-cross presented with a 24-h history of progressive paraparesis. Neurological examination was consistent with L4–S3 myelopathy. On magnetic resonance imaging (MRI), all vertebrae showed homogenously increased short tau inversion recovery (STIR) signal with strong contrast enhancement. The vertebral canal was concentrically narrowed along the length of the L5 vertebra secondary to bony proliferation of the vertebral pedicles, dorsal lamina, and vertebral body. Cytological analysis of the peripheral lymph nodes and subsequent flow cytometry was consistent with T-cell lymphoma. The dog was euthanised due to poor prognosis. Necropsy confirmed the presence of stage V multicentric T-cell lymphoma, as well as diffuse hyperostosis of the vertebral bodies. This is the first report of presumed paraneoplastic lumbar skeletal hyperostosis.

Magnetic Resonance Imaging Features of Extradural Spinal Neoplasia in 60 Dogs and Seven Cats

This retrospective study describes the MRI features of extradural spinal neoplasia in 60 dogs and seven cats to identify potential distinguishing features between tumor classes and individual tumor types within each class. In dogs, mesenchymal tumors were most common (48%), with undifferentiated sarcomas being the predominant tumor type. Round cell neoplasms were second most common (35%), with lymphoma and multiple myeloma/plasma cell tumor comprising the majority of cases. Only two benign tumors were identified. In cats, lymphoma was most common (5/7), with one case of mesenchymal neoplasia and one case of metastatic carcinoma. Despite some overlap, certain imaging features were able to help prioritize differential diagnoses. The combined features that predicted round cell neoplasia (84%) included the preservation of vertebral shape, homogeneous contrast enhancement, and lesion centering on bone. The combined features that predicted mesenchymal neoplasia (73%) included altered vertebral shape, heterogeneous contrast enhancement, and lesion centering on paraspinal soft tissues. Round cell neoplasms were more likely to have cortical sparing, preservation of overall shape, lesion centering on bone, small soft tissue tumor size, and homogeneous contrast enhancement. Both epithelial and mesenchymal neoplasms were more likely to have cortical lysis, a cavitary component to the soft tissue mass and medium to large soft tissue mass size. The findings of this study can aid in prioritizing differential diagnoses in cases of extradural spinal neoplasia in cats and dogs, which can impact case management, but tissue sampling remains the gold standard for definitive diagnosis.

Suspected Hypercalcemia of Benignancy Associated with Canine Vaginal Leiomyoma

Hypercalcemia was identified in a canine patient with a benign vaginal leiomyoma. Subsequent diagnostic workup did not reveal hypercalcemia of malignancy. Surgical resection of the leiomyoma resulted in a conversion to normocalcemic status. Although rare, hypercalcemia of benignancy should be considered in a patient in which hypercalcemia is identified via clinical pathology.

MAGNETIC RESONANCE IMAGING FINDINGS IN THE SPINE OF SIX DOGS DIAGNOSED WITH LYMPHOMA

Lymphoma is one of the most common neoplasms in the dog. Despite its prevalence and the increasing use of advanced diagnostic imaging in veterinary patients only few reports of magnetic resonance imaging (MRI) findings in spinal lymphoma have been published to date. The purpose of this retrospective case series study was to describe the MRI findings in dogs with confirmed lymphoma affecting the spine and/or paraspinal soft tissues. Medical records were searched for patients that had MRI of the spine and a diagnosis of lymphoma during the period of 2005-2015. Data recorded from retrieved MRI studies were presence of focal or multifocal disease, structures involved, and signal characteristics on T2-W, short tau inversion recovery (STIR), and T1-W sequences prior to and following intravenous contrast medium administration. Six dogs met the inclusion criteria. Common findings included multifocal disease (4/6), vertebral involvement (5/6), spinal cord compression (4/6), and involvement of more than one spinal compartment (medullary cavity, vertebral canal, paraspinal soft tissues) (6/6). Vertebral changes were confined to the medullary cavity without evidence of cortical osteolysis. There was questionable involvement of the spinal cord in one case. All spinal and paraspinal lesions identified were T2-W isointense to hyperintense, STIR hyperintense, T1-W hypointense to isointense, and showed variable moderate to strong contrast enhancement. Additional lesions identified were enlarged intraabdominal lymph nodes, hepatomegaly, splenomegaly, and a splenic nodule. The STIR and T1-W postcontrast sequences were subjectively the most useful in identification of the spinal and paraspinal lesions.

IMAGING DIAGNOSIS-VERTEBRAL POLYOSTOTIC LYMPHOMA IN A GERIATRIC DOG

A 9-year-old spayed female Scottish terrier presented with an 8-day history of progressive paraparesis. Neurological examination suggested a painful T3-L3 myelopathy. Multifocal uniform contrast-enhancing masses involving the vertebral bodies, pedicles, laminae, and spinous processes of two vertebrae and compressing the spinal cord were present on MRI. Fluoroscopic-guided fine needle aspiration of one of the vertebral lesions revealed a predominantly lymphoblastic population of cells compatible with a diagnosis of lymphoma. To the authors' knowledge, this represents the first published case of canine lymphoma with vertebral involvement, characterized with MRI.

Polyostotic lymphoma with multiple pathological fractures in a six-month-old cat

A 6-month-old female neutered domestic shorthair cat was examined for pain and swelling of the distal limbs. Swelling and malalignment of both carpi, dorsiflexion of the distal metatarsals and a mild, multicentric lymphadenopathy were detected on examination. Screening blood tests revealed a biclonal gammopathy, hypercalcemia and atypical leukocytes. Survey radiographs revealed lysis and proliferative changes within the physes. Multiple pathological physeal fractures were present, including the distal radii, metacarpal and metatarsal bones. No treatment was attempted and the patient was euthanased. Histopathology revealed infiltration by monomorphic round cells within the liver, spleen, kidney and bone marrow. Immunohistochemistry revealed strong reactivity to CD20. Clonality assays revealed clonal results for the B-cell loci, consistent with B-cell lymphoma. To the authors' knowledge this is the first report of polyostotic lymphoma with multiple pathological fractures in a cat. The predominantly distal distribution of osseous lesions is rarely reported in dogs and humans.

Metastatic angioinvasive lymphoma (lymphomatoid granulomatosis) in a cat

A subcutaneous mass removed from the right rear leg of a 17-year-old, spayed, female Domestic Shorthair cat was characterized histopathologically by granulomatous inflammation, sheets of large atypical lymphoid cells, and necrosis. The walls of the small and medium caliber blood vessels were invaded transmurally by atypical lymphoid cells. A diagnosis of angioinvasive lymphoma (AIL), or lymphomatoid granulomatosis, was made based on histopathologic findings. The cat was euthanized 2 months later because of recurrence of the mass and elevated serum alanine aminotransferase activity, and a necropsy was performed. The histopathologic lesion of AIL was seen in the skin and subcutis of the right rear leg, and neoplastic cell infiltrates were seen in adjacent skeletal muscle, right superficial inguinal lymph node, liver, and spleen. By immunohistochemistry, variable numbers of neoplastic cells expressed B-lymphocyte antigen 36 (BLA36) or cluster of differentiation (CD)3 markers, indicative of B- and T-cell lineages, respectively. Neoplastic cells were uniformly positive for vimentin and uniformly negative for cytokeratins and myeloid/histiocytic antigen. Although the cat had received a Rabies virus vaccine subcutaneously in the right rear leg 6 months earlier, the AIL lesion was not typical of vaccine-induced sarcomas. The AIL in this cat was unusual because the extrapulmonary metastases involved the skin and subcutis.