Congenital Suborbital Undifferentiated Sarcoma in a Crossbred Calf

SIMPLE SUMMARY: Congenital tumours are rare conditions in both veterinary and human medicine. Undifferentiated sarcomas represent a recently introduced section that encompasses unclassified sarcomas that have no distinct histologic, immunohistochemical, or genetic features. The aim of this study is to describe the clinical and pathological phenotype of a 3-day-old male crossbred calf presenting a congenital suborbital mass that infiltrated the underlying muscle and bone, and suggestive of undifferentiated sarcoma. To the best of our knowledge, our report constitutes the first clinical, ultrasonographic, radiographic, endoscopic and pathological study of a congenital undifferentiated sarcoma, a condition that has been rarely reported in the veterinary literature. ABSTRACT: Undifferentiated sarcomas are rare conditions that represent a group of unclassified sarcomas. The purpose of this study is to describe the clinical and pathological features of a calf showing a congenital infiltrating suborbital mass suggestive of undifferentiated sarcoma. The animal was referred because of respiratory distress and the presence of a right suborbital mass since birth. At ultrasonography, the mass displayed an irregular shape with multiple cavities. Radiographs revealed a diffuse, poorly defined mass with different densities overlying the bony structures of the skull. Endoscopy showed a co-involution of the mass in the right side with extension into the nasopharynx. Post-mortem examination showed a round, poorly demarcated neoplasia infiltrating the nasal turbinate and displacing the nasal septum. Histologically, the subcutis was expanded by lobules and bundles of densely cellular neoplastic spindle cells. The neoplasm infiltrated the underlying muscles, bone and the right retromandibular lymph node. The neoplastic cells had a diffuse intense cytoplasmic immunexpression to vimentin, and were negative to cytokeratin AE1/AE3, desmin, MUM1, IBA1, melan A, chromogranin and synaptophysin.