Mediastinal basaloid carcinoma arising from thymic cysts in two dogs.

Mediastinal masses in dogs were diagnosed as basaloid carcinoma associated with multiple thymic cysts (MTCs). The masses were composed of MTCs and proliferating intracystic neoplastic basaloid cells, which immunohistochemically diffusely expressed p63 and cytokeratin 19. A gradual transition from the basal cell layers lining the cysts walls to the neoplastic cells was seen, and it was indicated that the neoplastic cells had originated from the basal cell layers of the cysts. To the best of our knowledge, this is the first report of basaloid carcinoma occurring in the mediastinal cavity in dogs. Although these tumors were demonstrated to be rare origins, basaloid carcinoma should be included in the differential diagnoses for canine mediastinal tumors.

Clinicopathological characteristics and prognostic factors for canine multicentric non-indolent T-cell lymphoma: 107 cases.

Canine lymphoma, as the most common haematopoietic malignancy, encompasses a group of heterogeneous diseases and even within the T-cell immunophenotype, differences in clinical presentation and responses to treatment exist. The aim of this retrospective study was to determine outcomes and prognostic factors of 107 dogs with multicentric non-indolent T-cell lymphoma (TCL) receiving lomustine-based (70%) and non-lomustine-based (30%) treatment. The majority were Labradors, Boxers, mixed-breed dogs and Dogue de Bordeaux. Eighty-six percent were substage b, 77% had mediastinal involvement, 15% had suspected bone marrow involvement and 12% had other extra-nodal sites of disease. The overall response rate to induction therapy was 80%; dogs receiving procarbazine in the induction protocol (P = .042), dogs with neutrophil concentration below 8.7 × 10e9 /L (P = .006) and mitotic rate below 10 per 5 high power field (P = .013), had greater response rates. Median progression-free survival (PFS) for the first remission was 105 days; lack of expression of CD3 on flow cytometry (P < .0001) and pretreatment with steroid (P = .012) were significantly associated with shorter PFS. Median overall survival time (OST) was 136 days; co-expression of CD79a (P = .002), lack of CD3 expression on flow cytometry, presence of anaemia (P = .007), and monocytopenia (P = .002) were predictive of shorter OST. Multicentric non-indolent TCL in dogs is an aggressive cancer with new possible prognostic factors.

Mediastinal lymphoma in dogs is homogeneous compared to thymic epithelial neoplasia and is more likely to envelop the cranial vena cava in CT images.

In order to identify CT signs that could be used to distinguish cranial mediastinal lymphoma and thymic epithelial neoplasia, a retrospective case-control study was done. Associations between CT signs and diagnosis were tested using binary logistic regression and results expressed as odds ratio and 95% confidence interval. Sixty-two dogs that had thoracic CT and confirmed diagnosis of lymphoma (n = 33) or thymic neoplasia (n = 29) were sampled. Thymic neoplasms included 24 thymomas and five thymic carcinomas. Dogs with thymic epithelial neoplasia were significantly older than dogs with lymphoma (median age 8.6 years versus 6.0 years, P = .007), but there were no significant differences in prevalence of clinical signs. Diagnosis of thymic epithelial neoplasia was associated with heterogeneous attenuation in pre- (odds ratio 23.3, 95% confidence interval, 4.5-121.1) and post-contrast (odds ratio 30.7, 95% confidence interval, 3.6-265.0) images. Conversely, envelopment of the cranial vena cava by the mass was less likely with thymic epithelial neoplasia than lymphoma (odds ratio 0.07, 95% confidence interval, 0.007-0.66). Greater standard deviation of Hounsfield unit values in post-contrast images was associated with thymic epithelial neoplasia (P = .005). Based on ROC analysis, SD > 17HU of the mass in post-contrast images had a sensitivity of 72% and specificity of 79% for thymic epithelial neoplasia. There were no significant differences in morphology, prevalence of calcification, mediastinal lymphadenopathy, cranial vena cava invasion, collateral vessels, or pleural fluid associated with these tumors. Thymic epithelial neoplasms tended to occur in older dogs and were heterogeneous in CT images, whereas mediastinal lymphoma was more homogeneous and more likely to envelop the cranial vena cava.

Radiographic Differentiation of Cranial Mediastinal Lymphomas from Thymic Epithelial Tumors in Dogs and Cats.

In both dogs and cats, the most common cranial mediastinal masses (CMMs) are lymphoma and thymic epithelial tumors (TETs). Pretreatment differentiation of these tumors using fine needle aspiration or biopsy is essential because lymphomas are treated medically, whereas TETs are treated surgically. The purpose of this retrospective study was to determine whether thoracic radiographic findings can be used to aid clinicians in preliminarily differentiating the two tumor types before cytology or histopathology results become available. Medical records, available cytologic or histologic samples, and thoracic radiographs were evaluated for 62 dogs and 28 cats. Seventeen radiographic criteria were assessed by two examiners, and regression modeling was performed to test for significant predictors of tumor type. In dogs, CMMs with at least two well-defined radiographic margins on a lateral view and CMMs causing a rightward shift of the cardiac silhouette on a ventrodorsal or dorsoventral view were significantly more likely to be TETs than lymphomas (P < .001 and P < .01, respectively). No significant predictive variables were identified in cats. Radiographic findings do not eliminate the need for invasive sampling, but in dogs, they may guide the clinician in providing preliminary information to owners regarding the staging and therapeutic measures that may eventually be recommended.

Patient characteristics, prognostic factors and outcome of dogs with high-grade primary mediastinal lymphoma.

The goals of this retrospective study were to determine the patient characteristics of dogs with high-grade primary mediastinal lymphoma and to determine outcome and associated prognostic factors. A total of 42 dogs were identified, in which 36 received treatment and had follow-up information available. The most common clinical signs included lethargy, anorexia and polyuria/polydipsia. Hypercalcemia and pleural effusion were common findings at diagnosis. The phenotype was almost exclusively T-cell, most often in association with lymphoblastic cytomorphology as defined by the World Health Organization (WHO) lymphoma classification scheme. The overall progression-free survival (PFS) and overall survival (OS) were 133 and 183 days, respectively. Treatment with a CHOP (cyclophosphamide, doxorubicin, vincristine, prednisone) protocol was associated with an improved PFS (144 days) and OS (194 days) when compared with dogs that received other medical therapies (P = .005 and P = .002, respectively); the absence of pleural effusion at diagnosis was associated with an increased OS but not PFS. These results suggest that while the prognosis for dogs with mediastinal lymphoma is poor, survival may be improved with treatment using a CHOP-based protocol.

Acquired collateral venous pathways in a dog with cranial vena cava obstruction.

An 8-year-old neutered female Yorkshire terrier with mediastinal neoplasm and subsequent cranial vena cava invasion developed multiple venous collaterals from the brachiocephalic venous trunks to the caudal vena cava. Collateral venous pathways have been described in dogs with obstruction or increased blood flow resistance of the caudal vena cava but cranial vena cava collaterals have not been reported until now in veterinary patients. In this report, the CTA characteristics of such peculiar vascular routes are described and compared to similar findings reported in human medical literature. The recognition of such ancillary CT finding could help radiologists to reach a more accurate diagnosis of superior vena cava syndrome.

MEDIASTINAL LYMPHOMA AND CHYLOTHORAX IN A STRIPED SKUNK (MEPHITIS MEPHITIS).

Tumors are infrequently reported in skunks, with only a few case reports published in the literature. Chylothorax associated with mediastinal lymphoma was diagnosed in a captive 7-yr-old male striped skunk ( Mephitis mephitis ). The animal presented with anorexia and apathy. Supportive care and prednisolone improved the animal's clinical status for 2 wk preceding its death. Histopathology supported the clinical findings, and the tumor was classified as a mediastinal non-Hodgkin lymphoma, stage 2b, which has not been documented in the literature.

Video-assisted extirpation of cranial mediastinal masses in dogs: 18 cases (2009-2014).

OBJECTIVE To characterize clinical findings, surgical procedures, complications, and outcomes in dogs undergoing extirpation of masses from the cranial mediastinum via video-assisted thoracic surgery (VATS) and establish preliminary guidelines for case selection when considering VATS for thymectomy in dogs. DESIGN Retrospective case series. ANIMALS 18 client-owned dogs that underwent extirpation of a cranial mediastinal mass by means of VATS at 5 academic referral hospitals from 2009 through 2014. PROCEDURES Medical records were reviewed and data extracted regarding signalment, clinical signs, physical examination findings, diagnostic imaging results, surgical approach and duration, cytologic and histologic examination results, complications, outcome, and cause of death, when applicable. RESULTS 16 dogs had a thymoma, 1 had thymic anaplastic carcinoma, and 1 had hemangiosarcoma. Seven had both megaesophagus and myasthenia gravis. Median approximate tumor volume was 113.1 cm3 (interquartile range, 33.5 to 313.3 cm3). Median duration of VATS was 117.5 minutes (interquartile range, 91.5 to 136.3 minutes). Conversion to an open thoracic surgical procedure was required for 2 dogs, 1 of which died during surgery. Median survival time following VATS for dogs with thymoma and concurrent myasthenia gravis and megaesophagus was 20 days. Dogs with thymoma without paraneoplastic syndrome survived for ≥ 60 days, and none of these dogs died of disease-related causes. CONCLUSIONS AND CLINICAL RELEVANCE VATS appeared to be an acceptable approach for extirpation of masses from the cranial mediastinum in dogs under certain conditions. Dogs with myasthenia gravis and megaesophagus had a poor postoperative outcome.

Suspected bilateral phrenic nerve damage following a mediastinal mass removal in a 17-week-old pug.

The anesthetic management of a pediatric pug for removal of a mediastinal mass is described. During recovery from anesthesia, the dog's respiratory pattern was compatible with bilateral diaphragmatic paralysis. Incidence, complications, possible treatments of phrenic nerve injury, problems of long-term mechanical ventilation, and alternative case management are discussed.

Lésion bilatérale suspectée du nerf phrénique après l'ablation d'une masse médiastinale chez un Pug âgé de 17 semaines. Nous décrivons la gestion anesthésique d'un Pug pédiatrique présenté pour l'ablation d'une masse médiastinale. Durant le réveil après l'anesthésie, le profil respiratoire du chien était compatible avec la paralysie diaphragmatique bilatérale. L'incidence, les complications et les traitements possibles d'une blessure du nerf phrénique, les problèmes de la ventilation mécanique à long terme et les solutions pour la gestion du cas sont discutés.(Traduit par Isabelle Vallières).

Spontaneous mediastinal myeloid sarcoma in a common marmoset (Callithrix jacchus) and review of the veterinary literature.

BACKGROUND: Myeloid sarcoma is a rare manifestation of myeloproliferative disorder defined as an extramedullary mass composed of myeloid precursor cells. A 9-month old, female, common marmoset (Callithrix jacchus) had increased respiratory effort. METHODS: A complete necropsy with histology and immunohistochemistry was performed. RESULTS: The thymus was replaced by a firm, gray-tan mass with a faint green tint, filling over 50% of the thoracic cavity. Sheets of granulocytes, lymphoid cells, nucleated erythrocytes, megakaryocytes, and hematopoietic precursors of indeterminate cell lineage replaced the thymus, perithymic connective tissue, mediastinal adipose tissues, epicardium, and much of the myocardium. The cells demonstrated diffuse strong cytoplasmic immunoreactivity for lysozyme, and strong, multifocal membranous immunoreactivity for CD117. CONCLUSION: We report the first case of a myeloid sarcoma in a common marmoset (C. jacchus), similar to reported human cases of mediastinal myeloid sarcoma, and present a review of myeloproliferative diseases from the veterinary literature.

Concurrent cranial mediastinal Blastomyces granuloma and carcinoma with cranial vena caval syndrome in a dog.

This report describes an unusual progression of blastomycosis in a dog with concurrent mediastinal carcinoma. The dog was evaluated for respiratory distress. Diagnostic results revealed chylothorax and a cranial vena caval thrombus. Histopathology of the cranial mediastinal mass diagnosed mediastinal carcinoma and fungal granuloma. Intercurrent disease may complicate the clinical presentation and clinical course of blastomycosis.

Granulome médiastinal àBlastomyceset carcinome concomitant avec le syndrome d'une veine cave crâniale chez un chien. Ce rapport décrit une progression inusitée d'une blastomycose chez un chien atteint d'un carcinome médiastinal concomitant. Le chien a été évalué pour une détresse respiratoire. Les résultats diagnostiques ont révélé le chylothorax et un thrombus de la veine cave crâniale. L'histopathologie de la masse médiastinale crâniale a révélé un diagnostic de carcinome médiastinal et de granulome fongique. La maladie intercurrente peut compliquer la présentation clinique et l'évolution clinique de la blastomycose.(Traduit par Isabelle Vallières).

Portal site metastasis after thoracoscopic resection of a cranial mediastinal mass in a dog.

CASE DESCRIPTION: An 11-year-old castrated male Vizsla was evaluated for excision of a cranial mediastinal mass. CLINICAL FINDINGS: The dog had a 1-month history of a cough that had recently increased in frequency. On physical examination, the dog had a grade 2/6 left systolic heart murmur and multiple subcutaneous masses. A soft tissue mass was observed in the cranioventral aspect of the thorax on radiographs. Results of a CT scan revealed a well-defined, 2.8 × 3.2 × 3.9-cm soft tissue mass in the cranial mediastinum. TREATMENT AND OUTCOME: The dog underwent video-assisted thoracoscopic removal of the mediastinal mass and recovered routinely. Histologic examination of excised tissues revealed malignant thymoma. Approximately 6.5 months after surgery, the dog was evaluated because of polyuria, polydipsia, decreased appetite, and vomiting. On physical examination, masses were found in both axillary regions. Results of serum biochemical analysis indicated hypercalcemia. Thoracic ultrasonography revealed pulmonary metastases and a large mass in the right caudoventral region of the thorax. The dog received supportive care and medical treatment for hypercalcemia, but clinical signs recurred. Euthanasia was elected; necropsy and histologic examination revealed thymic carcinoma. CONCLUSIONS AND CLINICAL RELEVANCE: Descriptions of the development of portal site metastasis in canine patients are rare. In this patient, portal site metastasis developed rapidly after thoracoscopic resection of a malignant thymic mass and was associated with hypercalcemia. As use of thoracoscopic procedures increases in veterinary medicine, it will be important to monitor the development of major complications such as those in the patient of this report.