Secondary malignant lymphoma which simulated primary thyroid cancer.

A patient with secondary thyroid lymphoma who complained of a neck mass was presented. Multiple nodules were detected in both lobes of the thyroid gland, which appeared as homogeneous hypoechoic masses on ultrasonogarphy (US), low-density masses on computed tomography (CT), and areas of increased uptake on gallium-67 scintigraphy. The residual thyroid gland was normal. Surgery established a diagnosis of secondary thyroid lymphoma with no coexistent Hashimoto's thyroiditis but with cervical node involvement by lymphoma. Radiologic evidence of normal residual thyroid gland in a patient with thyroid lymphoma may be a sign of secondary thyroid lymphoma.