[Ultrasonography in the diagnosis of malignant lymphoma of the thyroid].

Malignant lymphoma of the thyroid was rare condition and it was difficult to make a diagnosis of malignant lymphoma preoperatively. Both ultrasonographic appearance and diagnostic significance of ultrasonography in malignant lymphoma of the thyroid were investigated in this study. Ultrasonography of 10 patients with malignant lymphoma of the thyroid was analyzed. Only 3 cases of 10 were diagnosed as malignant lymphoma by ultrasonography. Five cases were misdiagnosed as thyroid carcinoma, 1 as adenomatous goiter accompanied by cystic degeneration and 1 as chronic thyroiditis. Nine cases were nodular type i.e. limited extremely hypoechoic mass as contrasted with surrounding thyroid tissue, occupying asymmetrically in the thyroid gland. One case was diffuse type i.e. diffused hypoechoic area without surrounding residual thyroid tissue. The tumor size of the 2 cases in which no accumulation was observed in the 67Ga scintigram was 2 cm or less. By ultrasonography of these 2 cases, one case was diagnosed as malignant lymphoma and the other as thyroid carcinoma. Ultrasonography can be regarded to be very significant method as a screening test to make a diagnosis of malignant tumor for nodular type, especially small sized malignant lymphoma of the thyroid.