MAGNETIC RESONANCE IMAGING FEATURES OF INTRAVENTRICULAR EPENDYMOMAS IN Five CATS

Intraventricular ependymoma is a rare type of feline intracranial neoplasia and published information on magnetic resonance imaging (MRI) characteristics is currently lacking. The purpose of this retrospective case series study was to describe the clinical and MRI characteristics of histopathologically confirmed intraventricular ependymomas in a group of cats. Five cats met inclusion criteria. In relation to normal gray matter, ependymomas appeared hyperintense on T2W, T2W‐FLAIR, PD, and DW‐EPI images; isointense on ADC images; and had subtle to strong contrast enhancement. Some variability was seen on T2*GRE and on T1W images with masses being isointense to hyperintense. Four ependymomas were small and homogeneous, and one was centrally cavitated. All cats had obstructive hydrocephalus, transtentorial herniation, and foramen magnum herniation. Perilesional edema was identified in most cats but was questionable in one. Intraventricular ependymoma should be considered as a differential diagnosis for cats with this combination of MRI signs.     

Comparative vaccine-specific and other injectable-specific risks of injection-site sarcomas in cats

Objective-To compare associations between vaccine types and other injectable drugs with development of injection-site sarcomas in cats. Design-Case-control study. Animals-181 cats with soft tissue sarcomas (cases), 96 cats with tumors at non-vaccine regions (control group I), and 159 cats with basal cell tumors (control group II). Procedures-Subjects were prospectively obtained from a large pathology database. Demographic, sarcoma location, basal cell tumor, and vaccine and other injectable history data were documented by use of a questionnaire and used to define case, control, and exposure status. Three control groups were included: cats with sarcomas at non-vaccine sites, cats with basal cell tumors, and a combined group of cats with sarcomas at non-vaccine sites and cats with basal cell tumors. χ(2) tests, marginal homogeneity tests, and exact logistic regression were performed. Results-In the broad interscapular region, the frequency of administration of long-acting corticosteroid injections (dexamethasone, methylprednisolone, and triamcinolone) was significantly higher in cases than in controls. In the broad rear limb region, case cats were significantly less likely to have received recombinant vaccines than inactivated vaccines; ORs from logistic regression analyses equaled 0.1, with 95% confidence intervals ranging from 0 to 0.4 and 0 to 0.7, depending on control group and time period of exposure used. Conclusions and Clinical Relevance-This case-control study measuring temporal and spatial exposures efficiently detected associations between administrations of various types of vaccines (recombinant vs inactivated rabies) and other injectable products (ie, long-acting corticosteroids) with sarcoma development without the need to directly measure incidence. These findings nevertheless also indicated that no vaccines were risk free. The study is informative in allowing practitioners to weigh the relative merits and risks of commonly used pharmaceutical products.     

MAGNETIC RESONANCE IMAGING FEATURES OF THE TEMPOROMANDIBULAR JOINT IN NORMAL DOGS

Evaluation of the canine temporomandibular joint (TMJ) is important in the clinical diagnosis of animals presenting with dysphagia, malocclusion and jaw pain. In humans, magnetic resonance imaging (MRI) is the modality of choice for evaluation of the TMJ. The objectives of this study were to establish a technical protocol for performing MRI of the canine TMJ and describe the MRI anatomy and appearance of the normal canine TMJ. Ten dogs (one fresh cadaver and nine healthy live dogs) were imaged. MRIs were compared with cadaveric tissue sections. T1‐weighted (T1‐W) transverse closed‐mouth, T1‐W sagittal closed‐mouth, T1‐W sagittal open‐mouth, and T2‐W sagittal open‐mouth sequences were obtained. The condylar process of the mandible and the mandibular fossa of the temporal bone were hyperintense to muscle and isointense to hypointense to fat on T1‐W images, mildly hyperintense to muscle on T2‐W images, and were frequently heterogeneous. The articular disc was visible in 14/20 (70%) TMJs on T1‐W images and 13/20 (65%) TMJs on T2‐W images. The articular disc was isointense to hyperintense to muscle on T1‐W images and varied from hypointense to hyperintense to muscle on T2‐W images. The lateral collateral ligament was not identified in any joint. MRI allows evaluation of the osseous and certain soft tissue structures of the TMJ in dogs.     

CT angiography and MRI imaging features do not predict the tumor type and grade of feline injection site sarcoma

Computed tomographic angiography (CTA) and magnetic resonance imaging (MRI) have been described as methods for preoperative surgical planning in cats with feline injection site sarcomas (FISS), however, few published studies have compared these modalities. The objective of this retrospective, secondary analysis study was to determine if imaging features of FISS on CTA and MRI are predictive of neoplastic peritumoral projections. Archived data from a previous prospective study were retrieved for 10 cats with FISS. All cats had been evaluated in a single anesthetic episode with MRI and dual phase CT (CTA) imaging followed by surgical removal. Histopathological grading and targeted histopathology of imaging‐identified peritumoral projections were performed. Two observers evaluated the CTA and MRI studies for FISS shape, margination, size, enhancement pattern, postcontrast uniformity, pre‐ and postcontrast margination, the number of muscles involved, mass mineralization, and bone lysis. Metal was present in the imaging field of three of 10 cats, resulting in one nondiagnostic MRI. Peritumoral projections were detected in all cats with both imaging modalities, and most were benign. At least one neoplastic peritumoral projection was detected in six cats using MRI, five cats using CTA, and three cats with both modalities. Higher grade FISS were larger than low grade using MRI, and FISS were larger using MRI. Other FISS imaging features using MRI and CTA were similar. Findings supported use of either MRI or CTA for detecting neoplastic peritumoral projections in cats with FISS. Authors recommend CTA for cats with known metallic objects in the scan field.     

Retroperitoneal sarcomas in dogs: 14 cases (1992-2002)

OBJECTIVE: To describe the clinical features, surgical and histologic findings, biological behavior, and outcome of dogs with retroperitoneal sarcomas. DESIGN: Retrospective study. ANIMALS: 14 dogs. PROCEDURES: Medical and pathology records from 1992 to 2002 of dogs with tumors originating in the retroperitoneal space were reviewed. Dogs with retroperitoneal tumors originating from the adrenal glands, kidneys, or ureters were excluded. Inclusion criteria included observation of a tumor arising from the retroperitoneal space during exploratory surgery or necropsy and histologic confirmation of tumor type. Details of clinical signs, diagnostic findings, surgical management, and outcome were determined from medical records and telephone interviews with veterinarians and owners. RESULTS: Retroperitoneal sarcoma was diagnosed in 14 dogs, 2 at necropsy and 12 during exploratory surgery. Hemangiosarcoma was the most common histologic diagnosis. Seven dogs had regional extension of the sarcoma into adjacent organs, and 4 dogs had metastatic disease. Grossly complete resection was possible in 6 dogs. Cytoreductive surgery or incisional biopsy was performed in the remaining dogs. Two dogs were treated with palliative radiation therapy (1 intraoperatively and 1 postoperatively). Three dogs received adjunctive chemotherapy, although none completed the targeted course because of development of local recurrence or metastatic disease. Local recurrence was reported in 2 of 12 dogs and metastasis in 10 of 14 dogs. Thirteen dogs died or were euthanatized as a result of the retroperitoneal sarcoma; 1 dog was alive and disease-free 410 days after surgery. Median survival time was 37.5 days. CONCLUSIONS AND CLINICAL RELEVANCE: In dogs, retroperitoneal sarcomas are aggressive tumors with a high rate of local recurrence and metastasis, and a poor survival time.     

Diagnostic accuracy of pre‐treatment biopsy for grading soft tissue sarcomas in dogs

Histologic grade is an important prognostic factor for both local recurrence and metastatic potential with canine soft tissue sarcoma (STS). Pre‐treatment biopsy with identification of tumour grade may aid in prognostication and determination of surgical margins necessary for local control. The purpose of this study was to evaluate the grading accuracy of various pre‐treatment biopsy techniques (wedge, punch, needle‐core) for STS in dogs. Medical records of 68 dogs diagnosed with a STS via pre‐treatment biopsy and confirmed by excisional biopsy were evaluated. The concordance in grade between excisional and pre‐treatment biopsies was 59%. Of the 41% that lacked concordance, 29% of pre‐treatment biopsies underestimated and 12% overestimated grade. The method of pre‐treatment biopsy did not significantly effect grade concordance. Based on these data, needle‐core biopsy appears to be similar in accuracy compared to open biopsy, however, grading determined by pre‐treatment biopsy in general should be interpreted with caution.     

Multilobular tumor of bone in the mandible of a dog

An 8-year-old Siberian husky dog was presented for a mass involving the rostral mandible. Intraoral radiographs demonstrated diffusely irregular bone and displacement of all mandibular incisor teeth. The mass was diagnosed as a grade I multilobular tumor of bone based on incisional biopsy. A bilateral rostral mandibulectomy was performed with tumor negative margins. Oral examination at 14-months following surgery indicated normal healing with minimal side effects and no evidence of tumor recurrence.     

RADIOGRAPHIC CHARACTERIZATION OF PRIMARY LUNG TUMORS IN 74 DOGS

Primary pulmonary neoplasia is well recognized in dogs and prognosis depends upon the tumor type. The purpose of this retrospective study was to characterize the radiographic appearance of different primary lung tumors with the goal of establishing imaging criteria to separate the different types. Three‐view thoracic radiographs of 74 dogs with histologically confirmed pulmonary anaplastic carcinoma (n = 2), adenocarcinoma (n = 31), bronchioalveolar carcinoma (n = 19), histiocytic sarcoma (n = 21), and squamous cell carcinoma (n = 1) were evaluated. Radiographs were assessed for tumor volume, affected lobe, location within lobe, overall pulmonary pattern, presence of cavitation, mineralization, air bronchograms, lymphadenomegaly, and pleural fluid. Histiocytic sarcomas were significantly larger than other tumor types (271 cm³; P = 0.009) and most likely to be found in the left cranial (38%; 8/21) and right middle (43%; 9/21) lung lobes, whereas adenocarcinomas were most likely to be found in the left caudal (29%; 9/31) lung lobe. Fifty‐seven percent (12/21) of histiocytic sarcomas had an internal air bronchogram. Findings indicate that a large mass in the periphery or affecting the whole lobe of the right middle or left cranial lung lobe with an internal air bronchogram is likely to be an histiocytic sarcoma.     

Postoperative radiotherapy for canine soft tissue sarcoma

Thirty-five dogs with 37 soft tissue sarcoma tumors that were incompletely excised and treated with radiotherapy in the postoperative, adjuvant setting were reviewed. Variables evaluated included age, sex, tumor site, tumor histology, total tumor radiation dose, radiotherapy field size. time to recurrence, and survival. The majority of tumors were fibrosarcomas and hemangiopericytomas, but small numbers of other tumor types were also represented. Total tumor radiation dose ranged from 42 to 57 Gy given in 3- to 4.2-Gy daily fractions on a Monday through Friday schedule. Overall median survival was 1,851 days. Median time to local recurrence was greater than 798 days. Soft-tissue sarcoma tumors at oral sites had a statistically significant lower median survival (540 days) as compared to other tumor sites (2,270 days). Radiotherapy may be a useful adjuvant therapy for incompletely excised soft-tissue sarcomas with a reasonable expectation for long-term patient survival.     

The use of immunohistochemistry and the polymerase chain reaction for detection of feline leukemia virus and feline sarcoma virus in six cases of feline ocular sarcoma

Ocular sarcoma was diagnosed by light microscopic examination in enucleated globes ( n  = 4), orbital tissue biopsy ( n  = 1) and ocular evisceration contents ( n  = 1) from six cats. To determine if feline leukemia virus (FeLV) or a replication-defective FeLV, feline sarcoma virus (FeSV), was present in these ocular sarcomas, immunohistochemistry (IHC) and polymerase chain reaction (PCR) for FeLV were utilized. Immunohistochemical staining for FeLV glycoprotein 70 (gp70) was performed on all six formalin-fixed, paraffin-embedded tumors using an avidin–biotin complex technique. DNA was extracted from each specimen and a 166 bp region of the FeLV long-terminal repeat (LTR) was amplified by PCR. All tumors were composed primarily of spindle cells; two neoplasms had PAS-positive basement membrane enveloping areas of spindle cells. All tumors involved the uvea and five of six tumors showed transcleral extension, one of which invaded the optic nerve. Immunohistochemical staining for FeLV gp 70 was negative. PCR to amplify a portion of the FeLV LTR was negative. Based on these findings of these limited number of cases, FeLV/FeSV may not play a role in the tumorigenesis of feline ocular sarcomas. However, additional tumors representing all morphological subtypes should be investigated for the presence of viral antigen and DNA. It is important to determine the etiology and pathogenesis of these malignant ocular sarcomas. If the cell of origin and pathogenesis involve ocular and lenticular injury, and FeLV/FeSV is not present, then the clinical management of cases of feline ocular trauma, uveitis and glaucoma may prevent the development of this tumor.     

The effect of prednisone on histologic and gross characteristics in canine mast cell tumors

The objective of the study was to determine whether neoadjuvant prednisone therapy affects histological features of cutaneous and subcutaneous mast cell tumors. Twenty-eight dogs with a treatment naïve > 1-cm diameter mast cell tumor (MCT) were randomly assigned (Random number generator; Random.org, Dublin, Ireland) in a blinded fashion to receive either prednisone or placebo (Quality Food Center Pharmacy, Kirkland, Washington, USA). Volumes of mast cell tumors were calculated before incisional and excisional biopsies. Following incisional biopsy, patients received either prednisone (1 mg/kg body weight) daily or a placebo for 7 to 14 days leading up to excisional biopsy. Tumor grade for cutaneous MCT, and mitotic count and atypia for all tumors were reported. Perioperative treatment with prednisone had no significant effect on tumor grade, atypia, or mitotic count. Tumor volume was significantly decreased with prednisone treatment. The use of neoadjuvant prednisone to decrease MCT volume in order to facilitate tumor excision, can be considered without significant concern for change of tumor histologic features in the common population of low- to intermediate-grade MCT.     

Common malignant musculoskeletal neoplasms of dogs and cats.

Malignancies of the musculoskeletal system in dogs and cats can be categorized as either primary or metastatic within the bony or soft structures that comprise the musculoskeletal system. By far, the most common tumor that affects the musculoskeletal system in dogs is osteosarcoma. The most common tumors that affect the musculoskeletal system in cats are injection site sarcomas. These tumors are locally infiltrative; whereas up to 25% metastasize, most animals die from our inability to control local disease. The aim of this article is to provide a brief review of the biologic behavior of and treatment recommendations for common tumors of the musculoskeletal system, excluding the oral and nasal cavities.     

Sensitivity and specificity of methods of assessing the regional lymph nodes for evidence of metastasis in dogs and cats with solid tumors

OBJECTIVE: To determine sensitivity and specificity of physical examination, fine-needle aspiration, and needle core biopsy of the regional lymph nodes for evidence of metastasis in dogs and cats with solid tumors. DESIGN: Case series. ANIMALS: 37 dogs and 7 cats. PROCEDURE: Regional lymph nodes were evaluated by means of physical examination (palpation), fine-needle aspiration, and needle core biopsy. Results were compared with results of histologic examination of the entire lymph node, the current standard. RESULTS: Tumors included 18 sarcomas, 16 carcinomas, 7 mast cell tumors, and 3 other tumors. Carcinomas were more likely to have metastasized to the regional lymph node (7/16 animals) than were sarcomas (2/18). Sensitivity and specificity of physical examination were 60 and 72%, respectively. Sensitivity and specificity of cytologic examination of fine-needle aspirates were 100 and 96%, respectively. Sensitivity and specificity of histologic examination of needle core biopsy specimens were 64 and 96%, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that fine-needle aspiration may be a sensitive and specific method of evaluating the regional lymph nodes in dogs and cats with solid tumors, because results correlated well with results of histologic examination of the entire lymph node. Physical examination alone was not a reliable method and should not be used to decide whether to aspirate or biopsy the regional lymph nodes.     

Analysis of prognostic factors associated with injection-site sarcomas in cats: 57 cases (2001-2007)

OBJECTIVE: To identify prognostic factors in cats with injection-site sarcomas (ISSs). DESIGN: Retrospective case series. ANIMALS: 57 cats with ISSs. PROCEDURES: Medical records of cats were reviewed with regard to sex, age, anatomic site of tumor, tumor size, histologic grade, excision of a primary tumor versus excision of a recurrent ISS, use of excision alone versus excision plus adjuvant therapy, local tumor recurrence, and development of distant metastasis to predict overall survival time (ie, time from tumor excision to death). RESULTS: In univariate analyses, local recurrence and development of distant metastasis were significantly associated with survival time in cats. On multivariate analysis, development of distant metastasis remained a significant prognostic factor. Histologic grade was associated with distant metastasis, with cats having grade 3 tumors being significantly more likely to develop metastasis than cats with grade 1 and 2 tumors. Factors associated with local recurrence of ISSs were not identified. CONCLUSIONS AND CLINICAL RELEVANCE: The development of distant metastasis, which may occur later during the course of the disease, was identified as a prognostic factor for overall survival time in cats with ISSs. In addition, cats with histologic grade 3 ISSs should be considered for further interventional studies with chemotherapy to prevent the high rate of distant metastasis.     

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.     

Clinical and computed tomography tumour dimension assessments for planning wide excision of injection site sarcomas in cats: how strong is the agreement?

In injection site sarcoma (ISS) in cats lateral as well as deep margins should be correctly planned for a successful surgical outcome. The discrepancy between clinical and computed tomography (CT) measurements of dimension in resectable tumour has led to possible bias that affects the subsequent surgical dose. The aim of this study was to prospectively investigate the agreement between clinical and CT measurements of dimension in newly diagnosed ISS in cats. Fifty‐three client‐owned cats that underwent both clinical and CT measurements of the length and width of ISS were included. CT measurements showed a tendency towards being larger than clinical dimensions, and this difference increased with increasing tumour size. Based on our results, in further studies focusing on ISS in cats, the kind of assessment used to define tumour dimensions (CT versus clinic) should be declared and specified to properly consider surgical results and prognostic impact of this variable.     

Clinical indications and applications of radiotherapy and hyperthermia in veterinary oncology

The response of dogs and cats with neoplasia to radiation therapy has improved significantly during the past 10 years. This has largely been due to more aggressive radiation therapy treatment schedules, more accurate planning, and refinement of clinical indications. Sufficient numbers of dogs and cats irradiated with curative intent have not been accumulated to yet define the full impact of more aggressive therapy. However, many tumors will likely remain resistant to irradiation because of concomitant normal tissue injury that must be minimized. Systematic investigation of combination therapy (surgery, radiation, chemotherapy, and hyperthermia) should succeed in reducing local tissue side effects and increased local tumor control. A comprehensive approach to tumor management begins with decisions thoughtful of optimal treatment for suspected malignant tumors even at the time of initial examination and client counseling. An incisional biopsy provides essential information to determine the therapeutic course and should be considered prior to initial excision. More aggressive treatment, of even small tumors, early in the clinical course will lead to prolonged tumor control. Radiation therapy should be considered fundamental in the comprehensive treatment plan of many solid tumors.     

MR IMAGING OF HISTIOCYTIC SARCOMA OF THE CANINE BRAIN

Histiocytic sarcomas are characterized by proliferation and/or infiltration of neoplastic histiocytes localized to specific organs, unlike malignant histiocytosis which involves many organ systems. Only a few cranial histiocytic sarcomas have been reported. Here we describe four dogs that presented with neurological deficits referable to the forebrain, and were diagnosed histologically as having histiocytic sarcoma. Using magnetic resonance (MR) imaging, the tumors were characterized by a T2-hyperintense and T1-isointense mass in one dog, T2- and T1-isointense extraaxial masses in two dogs, and a diffuse T2-hyperintense lesion over the left cerebral cortex in one dog. All tumors had contrast enhancement. MRI features in three of the four dogs were similar to that of meningioma, supported by the observation of a dural tail in two of these three dogs, and a broad base of attachment in the other. In the other dog the imaging findings were similar to those of encephalitis. Intracranial histiocytic sarcoma does not appear to have specific MR imaging features and can be confused with meningioma or encephalitis.     

Multicenter case-control study of risk factors associated with development of vaccine-associated sarcomas in cats

OBJECTIVE: To determine whether particular vaccine brands, other injectable medications, customary vaccination practices, or various host factors were associated with the formation of vaccine-associated sarcomas in cats. DESIGN: Prospective multicenter case-control study. ANIMALS: Cats in the United States and Canada with soft tissue sarcomas or basal cell tumors. PROCEDURE: Veterinarians submitting biopsy specimens from cats with a confirmed diagnosis of soft tissue sarcoma or basal cell tumor were contacted for patient medical history. Time window statistical analyses were used in conjunction with various assumptions about case definitions. RESULTS: No single vaccine brand or manufacturer within antigen class was found to be associated with sarcoma formation. Factors related to vaccine administration were also not associated with sarcoma development, with the possible exception of vaccine temperature prior to injection. Two injectable medications (long-acting penicillin and methyl prednisolone acetate) were administered to case cats more frequently than to control cats. CONCLUSIONS AND CLINICAL RELEVANCE: Findings do not support the hypotheses that specific brands or types of vaccine within antigen class, vaccine practices such as reuse of syringes, concomitant viral infection, history of trauma, or residence either increase or decrease the risk of vaccine-associated sarcoma formation in cats. There was evidence to suggest that certain long-acting injectable medications may also be associated with sarcoma formation.     

Immunohistochemical detection of tumor suppressor gene p53 protein in feline injection site-associated sarcomas

Sarcomas associated with injection sites are a rare but important problem in cats. Immunohistochemical detection of p53 protein may correlate to mutation of the p53 tumor suppressor gene, a gene known to be important in oncogenesis. The expression of nuclear p53 protein in 40 feline injection site-assocated sarcomas was examined by immunohistochemical staining. In 42.5% (17/40), tumor cell nuclei were stained darkly; in 20% (8/40), tumor cell nuclei were stained palely; and in 37.5% (15/40), tumor cell nuclei were unstained. Immunohistochemical detection of p53 protein in a proportion of injection site-associated sarcomas suggests that mutation of the p53 gene may play a role in the pathogenesis of these tumors.