Anaplastic Thyroid Carcinoma

Epidemiology

Anaplastic thyroid cancer is one of the most aggressive malignancies of the head and neck. It constitutes almost 10% of all thyroid cancers. It occurs in older adults and is more common in females than in males. About 50% of anaplastic thyroid carcinomas are believed to arise in goiters and often coexist with other forms of thyroid cancer.

Clinical Features

Patients usually present with a rapidly enlarging thyroid mass. Other commonly associated symptoms include dyspnea, dysphagia, and hoarseness of voice due to pressure or invasion of the recurrent laryngeal nerve. Nodal or distant metastases occur in 80% of patients.

Pathology

Grossly, the tumor appears as a large firm mass with necrotic and hemorrhagic areas. It frequently replaces the entire thyroid gland and invades the surrounding soft tissues. Histologically, three morphological patterns are seen. These include the spindle cell, giant cell, and squamoid patterns. These patterns may often coexist. Cellular pleomorphism, high mitotic activity, necrosis, and pronounced invasiveness are typical histological findings.

Treatment

Total thyroidectomy followed by radiotherapy and chemotherapy is the most accepted form of treatment.

Imaging

US

The tumor is predominantly a large hypoechoic mass that replaces the involved lobe. The mass is often heterogeneous and frequently shows calcification (58%) and necrosis (78%) within.