Primary malignant glomus tumors of the thyroid gland: A case report

Malignant glomus tumors are rare mesenchymal tumors arising from the smooth muscle cells of the glomus body. Primary malignant glomus tumors of the thyroid are atypical. An 80-year-old man presented with a right thyroid tumor on computed tomography (CT) and was suspected of having multiple bilateral pulmonary metastases. The right lobe of the thyroid gland was accompanied by a low-density tumor and calcification inside, and infiltration into the trachea and cervical esophagus was deduced. Core needle biopsy (CNB) confirmed that round to polygonal atypical cells were growing in sheet form around the vascular endothelial cells. Immunohistochemistry results were positive for vimentin and smooth muscle actin (SMA) but negative for pan-cytokeratin and S-100 protein. Chemotherapy with doxorubicin was initiated. However, due to the progression of the disease, doxorubicin was replaced with pazopanib. His condition deteriorated further, and he died 3 months after the treatment. Overall, this disease has a poor prognosis.