A retrospective study of sinonasal tumors in 182 dogs treated with stereotactic radiotherapy (3 × 10 Gy) (2010-2015).

BACKGROUND: Stereotactic radiotherapy (SRT) is an emerging treatment for sinonasal tumors in dogs. Reported results regarding tumor control and incidence of acute and late radiation morbidities are inconsistent. OBJECTIVES: To determine treatment efficacy and prognostic indicators of SRT in dogs with sinonasal tumors and to quantify acute and late radiation morbidities. ANIMALS: One hundred and eighty-two client-owned dogs with sinonasal tumors diagnosed cytologically, histologically, or radiographically that underwent SRT. METHODS: Single-arm retrospective study by reviewing medical records of dogs treated with SRT (10 Gy × 3) between 2010 and 2015. Kaplan-Meier analysis was used to determine overall survival (OST; from the first day of SRT to death by any cause) and disease-specific survival times (DSST; OST but censoring tumor/treatment-unrelated death). Tumors were staged using modified Adams criteria. RESULTS: Median OST and DSST of dogs treated with 1 course of SRT was 441 (95% CI: 389-493 days) and 482 (428-536 days) days, respectively with skin/oral cavity acute morbidities observed in 3% of dogs. DSST in dogs with stage 4 disease showed no statistical difference compared to other stages (P = .64). Oro-nasal (n = 2) or naso-cutaneous (n = 11) fistula development occurred in 7.1% of dogs with median time of 425 days (range: 83-1733 days). Possible chronic rhinitis after SRT was recorded in 54 of 88 dogs (61%) where information was available. CONCLUSIONS AND CLINICAL IMPORTANCE: Results are comparable to other reports of treatment of SRT. Acute morbidities were minimal. Modified Adams stage scheme appeared to be inappropriate for prognostication for dogs with sinonasal tumors treated with SRT.

Lymphotropic nanoparticle magnetic resonance imaging for diagnosing metastatic lymph nodes in dogs with malignant head and neck tumours.

Lymphotropic nanoparticle magnetic resonance imaging (LNMRI) utilises ultrasmall paramagnetic iron nanoparticles (USPIOs) for imaging of metastatic lymph nodes in patients afflicted with cancer. LNMRI has been shown to be a highly effective and accurate way to diagnose metastasis in humans but has not been commonly reported on in veterinary medicine. USPIOs are phagocytised by macrophages and then localised to lymph nodes where they create a susceptibility artefact on gradient echo MRI sequences. In this study dogs (n = 24) with naturally occurring head and neck tumours were imaged with LNMRI then had mandibular and retropharyngeal lymph nodes extirpated for histological analysis. Subjective and objective analysis of the LNMRI images was performed and imaging results compared to histology as the gold standard. A total of 149 lymph nodes were included in this study. The overall sensitivity, specificity and accuracy was 64%, 94.4% and 89.3% respectively. However, if dogs with mast cell tumours were excluded from analysis the sensitivity, specificity and accuracy rose to 85.7%, 95.7% and 94.6%. LNMRI is potentially an accurate way to determine the presence of lymph node metastasis in dogs with some types of head and neck tumours. However, LNMRI has only moderate accuracy in dogs with oral or mucocutaneous mast cell tumours in this region.

Multi-modality imaging and therapeutics used in a case of canine spinal nephroblastoma.

A 4-year-old castrated male golden retriever dog was brought to a veterinary teaching hospital for evaluation of acute progressive paraparesis. Neurological examination indicated a spinal cord lesion between the third thoracic vertebra and third lumbar vertebrae. Magnetic resonance imaging (MRI) revealed an intradural, extra medullary, and/or intramedullary mass centered over the eleventh and twelfth thoracic disc space. The dog underwent cytoreductive surgery and histopathologic analysis diagnosed a nephroblastoma. Following this, the dog underwent multimodal therapy, including multiple surgeries, 2 courses of radiation, and combination chemotherapy. The dog had serial restaging using MRI, computed tomography (CT), and fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography throughout the course of therapy. The dog survived 350 d from date of first presentation until humane euthanasia was elected due to worsening of neurologic status. During postmortem examination, extensive infiltration of the spinal cord by nephroblastoma cells was discovered as well as pulmonary metastatic disease. Key clinical message: Based on the literature search, this is the first case in which surgery, radiation therapy, and chemotherapy were all used for the treatment of canine spinal nephroblastoma. This case report details the aggressive nature of a case of canine spinal nephroblastoma despite multi-modal therapy.

Méthode d'imagerie et de thérapies multimodales utilisées dans un cas de néphroblastome spinal canin. Un chien golden retriever mâle castré âgé de 4 ans a été présenté dans un hôpital d'enseignement vétérinaire pour l'évaluation d'une paraparésie progressive aiguë. L'examen neurologique a révélé une lésion de la moelle épinière entre la troisième vertèbre thoracique et la troisième vertèbre lombaire. L'imagerie par résonance magnétique (MRI) a révélé une masse intradurale, extra-médullaire et/ou intramédullaire centrée sur les onzième et douzième espace de disque thoracique. Le chien a subi une chirurgie de cytoréduction et une analyse histopathologique a diagnostiqué un néphroblastome. Par la suite, le chien a subi une thérapie multimodale, comprenant plusieurs interventions chirurgicales, deux cycles de radiothérapie et une chimiothérapie combinée. Le chien a subi une reclassification en série par MRI, tomodensitométrie (CT) et tomographie par émission de positrons au fluor-18 fluorodésoxyglucose/tomodensitométrie tout au long du traitement. Le chien a survécu 350 jours à partir de la date de la première présentation jusqu'à ce que l'euthanasie soit choisie en raison de l'aggravation de l'état neurologique. Au cours de l'examen post-mortem, une infiltration étendue de la moelle épinière par des cellules de néphroblastome a été découverte ainsi qu'une maladie métastatique pulmonaire.Message clinique clé :D'après la recherche documentaire, il s'agit du premier cas dans lequel la chirurgie, la radiothérapie et la chimiothérapie ont toutes été utilisées pour le traitement du néphroblastome spinal canin. Ce rapport de cas détaille la nature agressive d'un cas de néphroblastome spinal canin malgré une thérapie multimodale.(Traduit par Dr Serge Messier).

What Is Your Diagnosis?

In collaboration with the American College of Veterinary Radiology.

Clinical outcomes of thyroid tumours with concurrent epithelial and mesenchymal components in 14 dogs (2006-2020).

BACKGROUND: While rare, multiple individual case reports have described mixed thyroid tumours in dogs containing both epithelial and mesenchymal neoplastic components. OBJECTIVES: In this retrospective case series, we describe the clinical presentation, treatment and outcome of 14 dogs of canine thyroid tumours with concurrent mesenchymal and epithelial neoplastic populations. METHODS: Fourteen cases were retrospectively abstracted from nine institutions. Histopathologic samples and reports were collected from 10/14 dogs and reviewed by a single board-certified anatomic pathologist. RESULTS: All 14 dogs had curative-intent surgery to remove the thyroid neoplasm. The most common surgery performed was a unilateral thyroidectomy (10/14 dogs). Postoperatively, systemic therapy was administered in eight dogs. Six dogs developed local recurrence with a median time to loco-regional recurrence of 53 days. Ten dogs developed metastatic disease with the most common metastatic site being the lungs (6/10 dogs), with a median time to metastasis of 93 days. Ten dogs were euthanised due to locoregional or distant progression of their mixed thyroid neoplasm. The overall median survival time was 156 days (95%CI: 49-244). The median survival time for dogs treated with adjuvant therapy was 189 days (95%CI: 24-244), whereas dogs without adjuvant therapy had a median survival time of 156 days (95%CI: 35-upper limit could not be calculated; p = 0.62). CONCLUSION: The thyroid tumours with both mesenchymal and epithelial components in this small sample set were associated with a poor prognosis after surgical excision with or without adjunctive therapy.

Staging canine patients with appendicular osteosarcoma utilizing fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography compared to whole body computed tomography.

Few studies have investigated the diagnostic performance of fluorine-18-fluorodeoxyglucose (18 F-FDG) positron emission tomography/computed tomography (PET/CT) for staging veterinary patients with appendicular osteosarcoma. The purpose of this study was to evaluate the efficacy of 18 F-FDG-PET/CT compared to whole-body CT (WBCT) for staging canine patients with appendicular osteosarcoma. The 18 F-FDG-PET/CT imaging studies of 66 dogs with appendicular osteosarcoma were anonymized and separated into two detached studies (one with whole body pre- and post-contrast CT images and the other with the whole body pre- and post-contrast CT images with the associated 18 F-FDG-PET overlay). Image assessment was performed retrospectively by five board-certified veterinary radiologists. The radiologists were instructed to assign a predefined categorical score (1-4) to each pre-designated anatomic region based on a devised lesional scoring system. A score of 1 was normal, 2 abnormal but not neoplastic, 3 abnormal and concerning for neoplasia, and 4 abnormal, most likely neoplastic. Overall, the likelihood of detection of '3 or 4' was found to be significantly higher with 18 F-FDG PET/CT when compared to WBCT after adjusting for the effect of evaluator and the subject. Most significantly, 13 osseous lesions concerning for metastasis (scored 3-4) were identified in 10/66 dogs by at least one reviewer on 18 F-FDG PET/CT, which were not identified by any reviewer on WBCT. Additionally, four comorbid neoplastic lesions were identified with 18 F-FDG PET/CT and not with WBCT. The results of this study suggest that 18 F-FDG PET/CT is more efficacious in detecting metastatic and comorbid neoplastic lesions compared to WBCT in dogs with appendicular osteosarcoma.

What Is Your Diagnosis?

In collaboration with the American College of Veterinary Radiology.

The prognostic significance of metabolic tumour volume and total lesion glycolysis for dogs staged for appendicular osteosarcoma with fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography.

Metabolic tumour volumes (MTV) and total lesion glycolysis (TLG) are metabolic parameters that are becoming more commonly reported in human medicine to quantify tumours detected on fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (18 F-FDG PET/CT). In this retrospective study dogs afflicted with appendicular osteosarcoma that were staged with 18 F-FDG PET/CT had MTV and TLG at a variety of set and fixed thresholds calculated by two observers. These values, along with SUVmax , were evaluated for prognostic significance in this population of dogs. There was excellent correlation between two observers for all values. Multiple volumetric parameters were significantly associated with survival. SUVmax had the highest sensitivity for survival and TLG at 2.5 SUV*cm3 had the highest specificity for prediction of survival based on ROC calculations. The SUVmax , MTV at 2.5 SUV and TLG at 2.5 SUV*cm3 were significantly different between dogs that survived more than or less than 1 year. This study is the first of its kind in veterinary medicine that retrospectively evaluated volumetric tumour values for prognostic significance and may provide a basis for standardized method of reporting 18 F-FDG PET/CT results.

Use of stereotactic body radiation therapy for treatment of a pancreatic tumor in a cat.

CASE DESCRIPTION: A 16-year old castrated male domestic shorthair cat was evaluated at a veterinary teaching hospital because of polyuria, polydipsia, and weight loss of 2 months' duration. CLINICAL FINDINGS: Hematologic and biochemical examination results were within respective reference ranges except for moderately high pancreas-specific lipase concentration. Ultrasonographic and cytologic evaluation revealed a hepatic mass with findings consistent with mild cholestasis and inflammation and a pancreatic mass that was initially identified as a neuroendocrine tumor. TREATMENT AND OUTCOME: The cat underwent additional CT assessment and stereotactic body radiation therapy (SBRT; 3 fractions of 8 Gy, administered every other day) for treatment of the pancreatic tumor. Follow-up ultrasonographic and CT examinations indicated a partial response to SBRT, with a maximum CT-measured size reduction from 3.6 × 4.8 × 4.0 cm at the time of treatment planning to 2.0 × 2.0 × 1.9 cm 8 months later. Increased pancreatic tumor size and signs of carcinomatosis were detected 15 months after SBRT treatment; the initial cytologic diagnosis was changed to exocrine pancreatic carcinoma on reevaluation of the slides by another veterinary pathologist. Carboplatin treatment was elected, and signs of carcinomatosis resolved. The cat was euthanized without further testing because of weakness 589 days after SBRT was started. CLINICAL RELEVANCE: To the authors' knowledge, this is the first report of SBRT for suspected exocrine pancreatic carcinoma in a cat. Further investigation is needed to determine optimal fractionation schedules for SBRT of pancreatic tumors and utility of SBRT of exocrine pancreatic carcinoma in cats.

Retrospective analysis of use of fluorine-18 fluorodeoxyglucose-positron emission tomography/computed tomography (18F-FDG PET/CT) for detection of metastatic lymph nodes in dogs diagnosed with appendicular osteosarcoma.

The purpose of this retrospective analysis was to determine if fluorine-18 fluorodeoxyglucose-positron emission tomography/computed tomography (18F-FDG PET/CT) could potentially be an accurate staging tool for detecting metastatic lymph nodes in dogs with appendicular osteosarcoma based on the quantitative measurement of the maximum standard uptake value (SUVmax) of lymph nodes. A total of 53 dogs were identified that presented for staging via 18F-FDG PET/CT for primary appendicular osteosarcoma. Patients were categorized according to lymph node status of having either metastatic or non-metastatic nodes based on cytological or histological analysis. Maximum standard uptake (SUVmax) values of the sampled lymph node(s) were recorded and 3/77 (3.9%) of sampled lymph nodes were confirmed metastatic. A Mann-Whitney test revealed a statistical difference in the SUVmax of the metastatic versus non-metastatic lymph nodes [median: 6.6 to 95% confidence interval (CI): 2.56 to 14.37 versus 2.18 95% CI: 2.32 to 3.17, respectively, P-value = 0.05]. This retrospective analysis revealed a significant difference in the SUVmax as measured on 18F-FDG PET/CT between metastatic lymph nodes and non-metastatic lymph nodes in canine patients afflicted with appendicular osteosarcoma, in spite of the small numbers analyzed. While these results are promising, they should be interpreted with caution and further studies are justified.

Le but de cette analyse rétrospective était de déterminer si la tomographie par émission de positons avec le fluor-18 fluorodésoxyglucose/tomodensitométrie (18F-FDG TEP/CT) pourrait potentiellement être un outil de stadification précis pour la détection des ganglions lymphatiques métastatiques chez les chiens atteints d'ostéosarcome appendiculaire basé sur la quantification de la valeur standard maximale d'absorption (SUVmax) des ganglions lymphatiques. Les auteurs ont identifié 53 chiens qui furent classifiés avec le 18F-FDG TEP/CT pour l'ostéosarcome appendiculaire primaire. Les patients ont été classés, selon l'état des ganglions lymphatiques, à avoir des ganglions métastatiques ou non métastatiques sur la base d'une analyse cytologique ou histologique. Les valeurs d'absorption standard maximale (SUVmax) du ou des ganglions lymphatiques échantillonnés ont été enregistrées et 3/77 (3,9 %) des ganglions lymphatiques échantillonnés ont été confirmés métastatiques. Un test de Mann-Whitney a révélé une différence statistique du SUVmax des ganglions lymphatiques métastatiques versus non métastatiques [médiane: 6,6 à 95 % intervalle de confiance (IC): 2,56 à 14,37 versus 2,18 IC à 95 %: 2,32 à 3,17, respectivement, valeur de P = 0,05]. Cette analyse rétrospective a révélé une différence significative dans le SUVmax tel que mesuré sur 18F-FDG TEP/CT entre les ganglions lymphatiques métastatiques et les ganglions lymphatiques non métastatiques chez les patients canins atteints d'ostéosarcome appendiculaire, malgré le petit nombre analysé. Bien que ces résultats soient prometteurs, ils doivent être interprétés avec prudence et des études complémentaires sont justifiées.(Traduit par Docteur Serge Messier).

Flourine-18 fluorodeoxyglucose positron emission tomography imaging exhibits increased SUVmax at the level of the spinal intumescence in normal dogs.

Positron emission tomography (PET) imaging utilizing fluorine-18 labeled fluorodeoxyglucose is a relatively new imaging modality in veterinary medicine that is becoming more common for oncological staging and for musculoskeletal imaging. Thus, it is important to identify the normal variations on PET imaging that may be mistaken for pathology. Variation in standardized uptake values (SUVmax) have been anecdotally identified in the spinal cord of dogs undergoing fluorodeoxyglucose (FDG) PET-CT examinations for oncological staging, with notable increase in SUVmax values identified in the region of the cervical and lumbar spinal intumescences. The aim of this retrospective, analytical study was to compare the SUVmax values at four different locations throughout the spinal cord (C3, C5-T1, T13, and L3-S1) of a group of dogs with no evidence of neurologic disease and compare those findings to histologic specimens from dogs euthanized for unrelated disease. SUVmax values were significantly higher at the cervical and lumbar intumescences in comparison to the control regions (P < .0001 and P < .0001, respectively). Neuronal count and spinal cord gray matter area were also significantly greater at the cervical and lumbar intumescences (neuronal count P = .0025 and P = .0001; area P = .0004 and P = .0009, respectively) while overall neuronal density was lower (P = .003 and P = .028, respectively). We presume the increased SUVmax values at the spinal cord intumescences are the result of overall increased neuron count, increased proportion of gray matter, and increased spinal cord gray matter area. These findings will aid in the interpretation of future PET-CT studies and hopefully prevent the misdiagnosis of spinal cord disease in normal canines.

Ultrasonographic features of mesenteric cysticercosis in a domestic rabbit (Oryctolagus cuniculus).

A 5-year-old, 0.92-kg (2-lb), spayed female Dwarf Hotot rabbit was evaluated for a 1-day duration of lethargy and anorexia. Survey radiographs revealed evidence of gastrointestinal stasis. Abdominal ultrasonography characterized multiple small, round, anechoic structures embedded in the mesentery. These structures were thin walled with hyperechoic strands/septations. Most of the structures contained a well-defined, eccentric, hyperechoic nodule adherent to the intraluminal wall. Mesenteric cysticercosis was confirmed via exploratory laparotomy and histopathology. To the authors' knowledge, this is the first description of the ultrasonographic features of mesenteric cysticercosis in a domestic rabbit.

Potential for BioXmark liquid fiducial marker to improve identification of superficial component of canine oral tumors for computer-based radiation therapy planning.

The objective of this study was to evaluate a novel liquid fiducial marker, BioXmark, to improve identification of the superficial component of oral tumors in dogs with computed tomography imaging. Liquid fiducial marker was injected in 6 patients at the visible and palpable extent of each tumor. Gross tumor volumes with and without BioXmark were compared in terms of volume and conformity using a Paddick conformity index, Dice similarity coefficient, and gross tumor volumes mismatch analysis. All patients showed an increase in gross tumor volumes defined by BioXmark compared with the conventionally identified post-contrast gross tumor volumes contours. Volumetric conformity and gross tumor volumes mismatch analysis of the superficial component of gross tumor volumes resulted in a median conformity index of 0.61 and median Dice similarity coefficient of 0.76. The superficial gross tumor volumes showed a median increase of 47% when BioXmark was used. This study demonstrated a potential utility to combining liquid fiducial markers to post-contrast computed tomography images for improved oral tumor localization and gross tumor volumes contouring for radiation therapy planning.

Potentiel du marqueur de repère liquide BioXmark à améliorer l'identification d'éléments superficiels de tumeurs orales canines pour la planification de radiothérapie assistée par ordinateur. L'objectif de la présente étude était d'évaluer un nouveau marqueur de repère liquide, BioXmark, à améliorer l'identification des éléments superficiels des tumeurs orales canines par tomodensitométrie. Le marqueur de repère liquide fut injecté à six patients à la limite visible et palpable de chaque tumeur. Les volumes bruts des tumeurs avec et sans BioXmark furent comparés en termes de volume et de conformité en utilisant l'index de conformité de Paddick, le coefficient de similarité de Dice, et une analyse de disparité des volumes bruts des tumeurs. Tous les patients montrèrent une augmentation des volumes bruts des tumeurs déterminés par BioXmark comparativement aux volumes bruts des tumeurs déterminés par la méthode conventionnelle d'identification des contours post-contrastes. La conformité volumétrique et l'analyse de disparité des volumes bruts des tumeurs du composant superficiel des volumes bruts des tumeurs a résulté en un index de conformité médian de 0,61 et un coefficient de similarité de Dice médian de 0,76. Les volumes bruts superficiels des tumeurs montraient une augmentation médiane de 47 % lorsque le BioXmark était utilisé. La présente étude a démontré une utilité potentielle à combiner des marqueurs de repère liquides aux images de tomodensitométrie post-contraste pour améliorer la localisation de tumeurs orales et la détermination des volumes bruts des tumeurs pour la planification de la radiothérapie.(Traduit par Dr Serge Messier).

Prognostic value of fluorine18 flourodeoxyglucose positron emission tomography/computed tomography in dogs with appendicular osteosarcoma.

BACKGROUND: Factors indicative of a negative prognosis for appendicular osteosarcoma (OSA) in dogs are visible metastatic disease, location, and size of lesion. In human medicine maximum standard uptake value (SUVmax ), as measured on a fluorine18 flourodeoxyglucose positron emission tomography/computed tomography (18 F-FDG PET/CT), is prognostic for survival for several tumor types. OBJECTIVE: Determine if SUVmax is associated with progression-free interval (PFI) and determination of survival in dogs with appendicular OSA. ANIMALS: Sixty-two dogs with untreated appendicular OSA that had been staged with 18 F-FDG PET/CT. METHODS: Retrospective analysis of the 18 F-FDG PET/CT was performed. Dogs were excluded from the study if they did not receive definitive intent treatment for their primary OSA and adjuvant chemotherapy with carboplatin, or had visible metastatic disease on initial imaging. A region of interest (ROI) was created around the primary tumor to measure SUVmax . Univariable and multivariable Cox proportional hazards analysis was performed to evaluate for associations between variables including SUVmax and outcome of PFI and overall survival (OS). RESULTS: Maximum standard uptake value of the primary tumor was significantly associated with the OS (P = .04) with adjustment for treatment type and monocyte count. The overall median survival time (OST) was 284 days (range, 39-1293 days) with the OST of dogs having an SUVmax of ≥7.4 of 254 days (range, 98-428 days) and dogs with an SUVmax of <7.4 of 680 days (range, 108-811 days, P = .01). CONCLUSIONS AND CLINICAL IMPORTANCE: Maximum standard uptake value as measured via 18 F-FDG PET/CT is significantly associated with survival in dogs with appendicular OSA with a high SUVmax being an indicator of a negative prognosis.

Pilot study utilizing Fluorine-18 fluorodeoxyglucose-positron emission tomography/computed tomography for glycolytic phenotyping of canine mast cell tumors.

The goal of this prospective pilot study was to use naturally occurring canine mast cell tumors of various grades and stages as a model for attempting to determine how glucose uptake and markers of biologic behavior are correlated. It was hypothesized that enhanced glucose uptake, as measured by 2-[fluorine-18]fluoro-d-glucose-positron emission tomography/computed tomography (F18 FDG PET-CT), would correlate with histologic grade. Dogs were recruited for this study from a population referred for treatment of cytologically or histologically confirmed mast cell tumors. Patients were staged utilizing standard of care methods (abdominal ultrasound and three view thoracic radiographs), followed by a whole body F18 FDG PET-CT. Results of the F18 FDG PET-CT were analyzed for possible metastasis and standard uptake value maximum (SUVmax ) of identified lesions. Incisional or excisional biopsies of the accessible mast cell tumors were obtained and histology performed. Results were then analyzed to look for a possible correlation between the grade of mast cell tumors and SUVmax . A total of nine animals were included in the sample. Findings indicated that there was a correlation between grade of mast cell tumors and SUVmax as determined by F18 FDG PET-CT (p-value = 0.073, significance ≤ 0.1). Based on the limited power of this study, it is felt that further research to examine the relationship between glucose utilization and biologic aggressiveness in canine mast cell tumors is warranted. This study was unable to show that F18 FDG PET-CT was a better staging tool than standard of care methods.

Use of PET/CT and Stereotactic Radiation Therapy for the Diagnosis and Treatment of Osteosarcoma Metastases.

This case report describes the use of two new concepts in the diagnosis and treatment of metastatic osteosarcoma (OSA) in one dog. The dog was initially presented for positron emission tomography and computed tomography (PET/CT) as full-body staging following amputation and adjuvant chemotherapy for treatment of OSA of the proximal tibia. The initial PET/CT did not show evidence of metastatic disease. Six mo after OSA, diagnosis pulmonary metastatic nodules were identified and oral toceranib phosphate was initiated. Twelve mo postdiagnosis the dog developed neck pain and non-ambulatory tetraparesis and was diagnosed with a C7 vertebral metastatic lesion based on magnetic resonance imaging. A second PET/CT was performed to screen for further metastatic lesions, and a nodule within the right ischium was identified. The C7 and ischial lesions were treated with stereotactic radiation therapy (SRT). Sixteen mo postdiagnosis, a third PET/CT was performed due to increasing size of the pulmonary nodules and a right-sided liver metastasis was detected. The liver mass was treated with SRT. The PET/CT scans facilitated identification of gross metastatic lesions that were subsequently treated with SRT, which resulted in clinical improvement of the dog's neurological signs.

Treatment of extraskeletal osteosarcoma at a previous injection site resulting in prolonged survival in 1 dog.

A rare presentation of an extraskeletal osteosarcoma at a previous interscapular injection site in a dog is described. Treatment included surgical excision of the tumor followed by 6 rounds of intravenous carboplatin, oral toceranib, and cyclophosphamide. The dog survived for 20.5 months after diagnosis despite early development of pulmonary metastases.

Traitement d'un ostéosarcome extrasquelettique à un site d'injection antérieur produisant une survie prolongée chez un chien. Ce rapport décrit une rare présentation d'un ostéosarcome extrasquelettique à un site d'injection interscapulaire antérieur chez un chien. Le traitement a inclus l'excision chirurgicale de la tumeur suivie de six séries de traitement de carboplatine intraveineuse, de tocéranib oral et de cyclophosphamide. Le chien a survécu pendant 20,5 mois après le diagnostic malgré le développement précoce de métastases pulmonaires.(Traduit par Isabelle Vallières).

Stereotactic body radiation therapy for treatment of injection-site sarcomas in cats: 11 cases (2008-2012).

OBJECTIVE: To evaluate outcomes of stereotactic body radiation therapy (SBRT) in cats with injection-site sarcomas (ISS) via assessment of local responses and recurrences, survival times, and complications. DESIGN: Retrospective case series. ANIMALS: 11 cats with ISS. PROCEDURES: Medical records of cats that were treated with SBRT for ISS between June 2008 and July 2012 were reviewed; information on patient demographics (age, sex, and breed), oncological histories (including prior treatment and histologic grade), details of SBRT plans (tumor volume, treatment field sizes, and prescription), response to treatment (including toxicoses), progression-free intervals, and survival times were extracted. RESULTS: Acute radiation-associated toxicoses were infrequent and limited to mild, self-limiting dermatitis and colitis in 2 and 1 of the 11 cats, respectively. No late radiation-associated toxicoses were observed. The objective response rate was 8 of 11 cats; these patients either had a partial or complete response as determined on the basis of CT or physical examination findings. The median progression-free interval was 242 days, and the median overall survival time was 301 days; median follow-up time of censored subjects was 173 days. CONCLUSIONS AND CLINICAL RELEVANCE: SBRT was completed in 3 to 5 days and was well tolerated when used to treat cats with ISS. Measurable tumor responses were achieved in most cats in this study. Stereotactic body radiation therapy provided a means for palliation of ISS; further investigation is required to determine whether SBRT is a valid treatment option for downstaging disease prior to definitive surgery.