Primary Thyroid Sarcoma: A Systematic Review

Different types of malignant tumors can occur within the thyroid. Primary cancer is the most common type of thyroid malignancy. Non-epithelial malignancies can also arise within the thyroid. The aim of the present study was to analyze clinical and radiological characteristics of reported primary thyroid sarcomas (PTS), based on a large sample of cases. The PubMed database was screened for articles from between 1990 and 2014. Overall, 86 articles with 142 patients were identified. Ultrasound evaluation was reported for 36 patients. Data regarding computed tomography of the neck were available for 29 cases. Magnetic resonance imaging was performed for eight patients. The following data were retrieved for the identified sarcomas: localization, size, homogeneity, internal texture, and margin characteristics. In most cases, PTS occurred in patients over 40 years of age, with a peak incidence for the group aged 60-79 years. Angiosarcoma was diagnosed in 29 cases (20.4%), followed by malignant hemangioendothelioma (n=23, 16.3%), malignant fibrous histiocytoma (n=20, 14.1%), leiomyosarcoma (n=16, 11.3%), and fibrosarcoma (n=13, 9.2%). In most patients (n=113, 79.6%), PTS manifested clinically as a painless goiter. On ultrasound, PTS were predominantly mixed hypo-to-hyperechoic in comparison to the normal thyroid tissue. On non-contrast computed tomography, most sarcomas were inhomogeneous hypo-to-hyperdense. On post-contrast magnetic resonance images, most sarcomas showed marked non-homogenous enhancement. In 26.8%, infiltration of the adjacent organs was seen. The trachea or esophagus was affected more frequently in patients with malignant histiocytoma and liposarcoma. Different strategies were used in the treatment of PTS. Our analysis provides clinical and radiological characteristics of PTS. The described features should be taken into consideration in the differential diagnosis of thyroid tumors.