Primary thyroid lymphoma: evaluation with US, CT, and MRI

Our goal was to determine the most effective radiologic workup in diagnosing and staging primary thyroid lymphomas and the value of knowing the extent of tumors for prognostic purposes.

Magnetic resonance imaging, CT, US, and fine-needle aspiration (FNA) biopsy (palpation- or US-guided) findings were retrospectively reviewed in 14 patients with primary thyroid lymphomas (5 palpable, 9 nonpalpable). Survival was correlated with the presence or absence of extrathyroidal spread of lymphoma.

Thyroid lymphomas were detected in all patients with US and 12 (86%) each with CT and MRI. Histopathologic diagnosis was obtained with FNA in 11 patients (79%) and with surgical procedures in 3. Magnetic resonance imaging correctly diagnosed tumor involvement of the lymph nodes (four of four patients), muscle (five of five), esophagus (one of one), internal jugular vein (one of one), and carotid artery (one of one). Muscle invasion was missed with CT in one patient. Ultrasound was not accurate for diagnosing tumor invasion of the esophagus, carotid artery, and lymph nodes. The survival of patients without extrathyroidal spread was significantly (p < 0.05) better than that of patients (n = 5) with extrathyroidal spread.

Palpable thyroid masses should undergo palpation-guided FNA for diagnosis and nonpalpable masses US-guided FNA. Tumor extent and staging should be determined with MRI, which will contribute to initiating appropriate therapy and prediction of prognosis.