Thyroid Lymphoma of Mucosa-Associated Lymphoid Tissue with Monoclonal Gammopathy Occurring in an Atomic Bomb Survivor: Report of a Case

We describe herein a case of thyroid lymphoma of the mucosa-associated lymphoid tissue (MALT) with mono- clonal gammopathy (IgG kappa), occurring in a woman who was exposed to atomic-bomb (A-bomb) radiation 1.5 km from the explosion of the hypocenter when she was 31 years old. Her estimated radiation dose was 0.2 Gy. A total thy- roidectomy resulted in the disappearance of monoclonal gammopathy, thus indicating extramedullary monoclonal gammopathy of the thyroid. Three patterns of protein elec- trophoresis, i.e., normal, the appearance of monoclonal immunoglobulins, and their disappearance after the total thyroidectomy, were consecutively recorded. The utility of checking of the monoclonal immunoglobulin levels after a thyroidectomy due to lymphoma of the MALT to monitor recurrence is therefore suggested. This lymphoma is most likely not related to the patient's A-bomb radiation exposure.