Thyroid carcinosarcoma

From Dog
Microscopic appearance of a thyroid carcinosarcoma, showing spindle-shaped neoplastic cells lining and interspersed between irregular trabeculae of osteoid (arrow)[1]

Thyroid carcinosarcoma are a rare malignant canine thyroid gland tumor, usually affecting older dogs and characterized by tumors composed of both carcinoma and sarcoma with osseous elements[1].

These tumors consist of both malignant epithelial (follicular cells) and mesenchymal (usually osteogenic or cartilaginous or both) elements[2]. Other reported sites where primary carcinosarcomas may arise in dogs are the mammary gland[3], lung[4], salivary gland[5], ceruminous gland[6], and eyelid[7].

These tumors often grow rapidly and invade adjacent structures such as the trachea, esophagus, and larynx[8]. Lung is the earliest and most frequent site of metastasis for thyroid carcinomas because these tumors tend to invade branches of the thyroid vein[9]. Ectopic tumors may also be observed in other organs such as the heart[10]. 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.

Paraneoplastic hypercalcemia may be observed in these canine cases.

Diagnosis is based on clinical history, symptoms and supportive imaging to assess possible metastases within the abdomen or chest.

A differential diagnosis would include thyroid adenoma, thyroid carcinoma, thyroid adenocarcinoma, chondrosarcoma and oncocytoma.

In localized resectable cases, thyroidectomy may be curative with adjunctive therapy including doxorubicin and carboplatin.

metastatic cases are usually associated with a poor prognosis.


  1. 1.0 1.1 Grubor B & Haynes JS (2005) Thyroid carcinosarcoma in a dog. Vet Pathol 42(1):84-87
  2. Capen CC (2002) Tumors of the endocrine glands. In: Tumors in Domestic Animals, ed. Meuten DJ, 4th ed., pp. 638–684. Iowa State Press, Ames, IA
  3. Benjamin SA et al (1999) Classification and behavior of canine mammary epithelial neoplasms based on life-span observations in Beagles. Vet Pathol 36:423–436
  4. Salas G et al (2002) Lung carcinosarcoma in a dog: gross and microscopic examination. Vet J 163:331–334
  5. Perez-Martinez C et al (2000) Malignant fibrous histiocytoma (giant cell type) associated with a malignant mixed tumor in the salivary gland of a dog. Vet Pathol 37:350–353
  6. Moisan PG & Watson GL (1996) Ceruminous gland tumors in dogs and cats: a review of 124 cases. J Am Anim Hosp Assoc 32:449–453
  7. Hirai T et al (1997) Apocrine gland tumor of the eyelid in a dog. Vet Pathol 34:232–234
  8. Johnson JA & Patterson JM (1981) Multifocal myxedema and mixed thyroid neoplasm in a dog. Vet Pathol 18:13–20
  9. Fernandez NJ et al (2008) What is your diagnosis? Ventral neck mass in a dog. Vet Clin Pathol 37(4):447-451
  10. Almes KM et al (2008) Intracardiac ectopic thyroid carcinosarcoma in a dog. Vet Pathol 45(4):500-504