ETA2024 Poster Presentations Anaplastic thyroid cancer (10 abstracts)
1Somdech Phra Debaratana Medical Center, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Medicine, Bangkok, Thailand; 2Department of Pathology, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand; 3Somdech Phra Debaratana Medical Center, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand; 4Somdech Phra Debaratana Medical Center, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Thailand; 5Department of Medicine, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
Introduction: Thyroid gland fibrosarcomas are very rare tumors, with only very few cases have been reported in the literature. Their similarity to anaplastic thyroid cancer poses a diagnostic challenge, often leading to misdiagnosis.
Case Report: We report the case of an 87-year-old female with a history of left thyroid nodule who underwent a left lobectomy and subsequently received levothyroxine therapy. She presented with a rapidly growing mass on the right thyroid gland. Her thyroid function was normal. Ultrasound revealed an ill-defined hypoechoic mass measuring 4 cm on the right thyroid. Fine-needle aspiration biopsy was performed, and cytology indicated Bethesda VI for anaplastic thyroid carcinoma. After the total thyroidectomy, the surgical pathological examination revealed a high-grade fibrosarcoma with extension into the strap muscle. Lymphovascular and perineural invasion was noted. Immunohistochemical staining showed positivity for smooth muscle actin, and negative for PAX8, TTF1, and thyroglobulin. Following surgery, adjuvant therapy with radiation and chemotherapy using ifosfamide was administered. However, the disease progressed with lung metastasis. The treatment was changed to administration of pazopanib, resulting in dramatic improvement of lung metastasis. However, the disease continued to progress, and patient passed away within 2 years after treatment initiation.
Conclusions: Although fibrosarcoma of the thyroid gland is exceedingly rare, it should be considered in the differential diagnosis of anaplastic thyroid carcinoma. Immunohistochemistry plays a crucial role in supporting the diagnosis. A multidisciplinary approach is essential for its management. In addition to surgery, emerging adjuvant therapies with kinase inhibitors have shown promise in improving patient survival.