IMAGISTIC AND CYTOLOGICAL DIAGNOSIS IN A CASE OF MEDIASTINAL MESENCHIMAL NEOPLASIA IN DOG Cristina BARBAZAN, Geta PAVEL, Eusebiu INDILAR, Andrei BAISAN, Elena GAVRILA , Vasile VULPE University of Agricultural Sciences and Veterinary Medicine, Faculty of Veterinary Medicine, Clinics Department, 8 M. Sadoveanu Alley, 700489, Ia i, Romania. Corresponding author e-mail: cristina_serbanmv@yahoo.com Abstract This paper presents the case of a female dog with a mediastinal mass. Clinical, imagistic and cytological evaluation of the patient are presented. A 4 years old female Rottweiler was referred to FMV Iasi Clinics with signs of respiratory distress resistent to treatment. Clinical examination of the dog revealed paroxostic, productive cough, harsh respiratory sounds, fever and regurgitation. Radiographs of the spine and thorax in right and left lateral and dorso-ventral incidence revealed a large mass occupying the cranial mediastinum and left cranial thorax, pushing the heart and the carina caudally and the esophagus and the trachea laterally, to the right. The esophagus was dilated cranially due to external mass compression and aspiration pneumonia signs were found in the lung. Small nodular mases were also seen in all the lung lobes. Endoscopy of the esophagus and trachea revealed the integrity of these organs and external compression. Ultrasound examination showed an hperechoic heterogenous mass. Ultrasound-guided fine-needle aspiration of the mass was performed. The cytological examination of the samples showed necrosis and a pleomorphic cell population with obvious malignancy criterias: macrocytosis, anisocytosis, anisocaryosis, multiple nucleoli, numerous mytosis, high N/C ratio. The pleomorphic aspect of the mesenchymal cell population prevented a clear classification of the tumour but revealed a high malignancy mesenchymal mediastinal neoplasia. The differential was made between extra-skeletal osteosarcoma/chondrosarcoma, hemangiopericitoma and fibrosarcoma. Keywords: mediastinal mass, ultrasound guided aspirate, cytology, extra-skeletal osteosarcoma INTRODUCTION In veterinary medicine, as in human one, the main problem about the neoplasias and their approach/therapies resides in the time that passes until a right diagnosis and prognosis is made. The later the tumour is discovered, the higher the chances are that the malignant transformation has begun or even worse, the metastatic disease has spread. The external visible masses (skin, muscles, bony structures) are easier to see and still the patients get to a medical control usually when it’s too late, with gross deformities and ulcerated growths. The internal masses are even harder to spot in the beginning of the disease, and only when the functions of the affected organs are altered or when the paraneoplasic syndroms begin, the owners notice signs of disease on their pet-friend and they start investigating. Rarely internal masses are discovered at routine surveys, only a small part of pet-owners have annual routine check controls of blood, abdominal ultrasound and thoracic radiographs. Thoracic masses may affect the lung, the pleural space, the thoracic wall or the mediastinum. They may be primery tumours or metastatic disease. Mediastinal masses may be localised in four regions (cranio-ventral mediastinum, cranio- dorsal mediastinum, caudo-ventral mediastinum and caudo-dorsal mediastinum) and, depending on that, they may or may not involve particular organs and they include different pathologies. Cranial mediastinal masses (dorsal or ventral) include in their differential diagnosis tumours of neural or neuro-endocrine origin, paravertebral or vertebral tumours, chemodectomas, thymomas, lymphomas (thymus or lymphnodes lesions), ectopic thyroid or parathyroid masses, pericardial chyst ot teratomas. (1) They usually don’t produce clinical signs at the beginning, and they remain 58 Scientific Works. Series C. Veterinary Medicine. Vol. LIX (3) ISSN 2065-1295, ISSN Online 2067-3663, ISSN-L 2065-1295