These tumors consist of both malignant epithelial (follicular cells) and mesenchymal (usually osteogenic or cartilaginous or both) elements. Other reported sites where primary carcinosarcomas may arise in dogs are the mammary gland, lung, salivary gland, ceruminous gland, and eyelid.
These tumors often grow rapidly and invade adjacent structures such as the trachea, esophagus, and larynx. Lung is the earliest and most frequent site of metastasis for thyroid carcinomas because these tumors tend to invade branches of the thyroid vein. Ectopic tumors may also be observed in other organs such as the heart. They
Clinically affected dogs often present with a palpable subcutaneous lump in the ventral cervical region, together with symptoms referable to hyperthyroidism, including panting, polydypsia and polyuria, weight loss, hind limb weakness and weight loss.
Diagnosis is based on clinical history, symptoms and supportive imaging to assess possible metastases within the abdomen or chest.
metastatic cases are usually associated with a poor prognosis.
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