Primary thyroid mucosa-associated lymphoid tissue lymphoma; a clinicopathological study of seven cases.

Purpose: Primary thyroid mucosa-associated lymphoid tissue (MALT) lymphoma is a very rare subgroup of thyroid lymphoma, accounting for about 6 to 28% of all primary thyroid lymphomas. The purpose of this study was to evaluate its clinicopathological features and treatment outcomes.

Methods: We identified seven patients with thyroid MALT lymphoma who were treated between January 1997 and December 2007, and reviewed their clinicopathological features and follow-up outcomes.

Results: There were five female and two male patients, and their mean age was 73 years. All patients presented with palpable neck mass. Two patients had hoarseness and dyspnea. All patients had a history of Hashimoto's thyroiditis with a mean of 175 months. Malignant lymphoma was suspected in only three patients using core needle biopsy. Four patients underwent thyroidectomy in the absence of preoperative pathologic confirmation, and histologic diagnosis was obtained after surgery. As initial treatment, complete surgical resection was performed in five patients, radiotherapy in one, and a combination of chemotherapy and radiotherapy in one. Six patients were alive for the mean follow-up period of 66 months and one patient died of unrelated causes. There were neither recurrences nor disease-specific mortalities.

Conclusion: When primary thyroid MALT lymphoma occurs in the thyroid or is confined to the neck, it responds well to local treatment such as surgical resection and external beam radiation therapy.