Primary thyroid marginal zone B-cell lymphoma of the mucosa-associated lymphoid tissue type: Clinical manifestation and outcome of a rare disease - Consortium for improving survival of lymphoma study

Purpose: Primary thyroid marginal zone B-cell lymphoma of the mucosa-associated lymphoid tissue type (pTY-MZL) is an extremely uncommon form of lymphoma. Due to its rarity, the natural history and optimal treatment modality for this disease have yet to be clearly established. Methods: A total of 27 patients with histologically confirmed pTY-MZL were retrospectively analyzed. Results: The median age of our subjects was 53 years (range 25-82). This study involved 17 females (63.0%) and 10 males (37.0%). Twenty-four out of 27 patients (88.9%) initially presented with localized disease, defined by Ann Arbor stage I/II. Bone marrow involvement was detected in 8.3% of the patients (2 patients), and 91.7% of the patients (25 of 27) were categorized into the low or low-intermediate risk group, according to the International Prognostic Index criteria. Accompanying Hashimoto's thyroiditis was detected in 72% of the patients, whereas thyroglobulin antibody levels were elevated in 70% of the patients. Twenty-six patients were treated with surgery, radiotherapy or chemotherapy, and 25 patients achieved complete remission. During the follow-up period, only 2 patients evidenced progression, and no deaths occurred over the course of the study. Conclusion: pTY-MZL tends to be an indolent disease. However, unlike other mucosa-associated lymphoid tissue site MZLs, pTY-MZL was well controlled via several treatment modalities, and the patients' responses were sustained for a prolonged period.