A case report of malignant lymphoma with Hashimoto's thyroiditis

The authors studied a case of malignant lymphoma arising in a patient with Hashimoto's thyroiditis. Histologically, a malignant, large cell, immunoblastic lymphoma was revealed, with the surrounding area showing changes typical of Hashimoto's thyroiditis. Immunoperoxidase staining proved the lymphoma cells to have intracytoplasmic immunoglobulins (IgA, k). Infiltrating interfollicular plasma cells containing the same kind of intracytoplasmic immunoglobulins (IgA, k) were present in the surrounding Hashimoto's thyroiditis lesions. Thus, it is possible that the interfollicular infiltrating plasma cells evolved into a malignant lymphoma in this case of Hashimoto's thyroiditis.