Introduction

Carcinosarcomas are malignant mixed tumors that contain both epithelial and mesenchymal cells components on histopathology. These tumors have been reported in the mammary gland, lung, salivary gland, uterus and, in at least 8 case reports, the thyroid of dogs.

Methods

In this retrospective study, we describe the clinical presentation, treatment, and outcome of 14 cases of canine thyroid carcinosarcoma (TCS). Histopathologic samples were collected from 10/14 cases and reviewed by a single board-certified anatomic pathologist (histopathological data collection in progress.)

Results

All 14 dogs had curative-intent surgery to remove the thyroid neoplasm. The most common surgery performed was marginal excision with a unilateral thyroidectomy (10/14 dogs). Post-operatively, systemic therapy was administered in 8 dogs. Six dogs developed local recurrence of the TCS, with a median time to recurrence of 156 days (95% CI: 49—not calculated). Ten dogs developed metastatic disease with the most common metastatic site being the lungs (6/9 dogs), with a median time to metastasis of 92.5 days (0—not calculated days). Ten dogs were euthanized due to local or distant progression of the TCS. The overall median survival time was 156 days (95% CI: 49–244).

The median survival time for dogs treated with adjuvant therapy was 189 days (95% CI: 24–244) while dogs without adjuvant therapy had a median survival time of 156 days (95% CI: 35–156; p=0.62).

Conclusion

TCS are an uncommon neoplasm of the dog and appear to have a poor prognosis after surgical excision with or without adjunctive therapy.

Funding Information

No funding was used for this project.