POSTPARTUM SILENT THYROIDITIS SIMULATING A MALIGNANT-LYMPHOMA OF THE THYROID

A case of postpartum silent thyroiditis simulating a malignant lymphom a of the thyroid is reported. The patient was a 30-yr-old female who h ad received irradiation therapy to the neck for malignant lymphoma of the thyroid 9 yr previously. She was referred to our department becaus e of a struma associated with acute aggravation of chronic thyroiditis after parturition. In this case, the mechanism bf the disease was exp lained by the ''immune rebound hypothesis.'' It was difficult to diffe rentiate postpartum silent thyroiditis from malignant lymphoma of the thyroid, either clinically or cytologically, when the immune-rebound p henomenon with lymphocytic infiltration and the appearance of lymphoid follicles were prominent. The immunological status of patients with c hronic thyroiditis accompanied by morphological changes should be take n into consideration before establishing the diagnosis of malignant ly mphoma of the thyroid.