[Evolution of chronic lymphocytic thyroiditis in primary malignant lymphoma in an extranodal location].

Primary malignant lymphoma of extranodal localization is a rare disease which mainly occurs in organs with greater or less quantity of lymphocytic tissue or in the organs with the previous history of lymphocytic infiltrate. Extranodal localization of malignant lymphoma in the thyroid gland is rare and numerous authors associate it with the previous existence of chronic lymphocatic thyroiditis (Hashimoto struma). This paper dealt with the histologically analysed material obtained by subtotal or total thyreoidectomy over one-year period. Out of 49 cases, histologic diagnosis of chronic diffuse lymphocytic thyroiditis was established in nine patients (18%) but the frequency of the appearance of this autoimmune disease may well be grater because a relatively small number of patients underwent the operation. Apart from all morphologic characteristics of Hashimoto struma, primary malignant lymphoma of extranodal localization in the thyroid gland was diagnosed in one patient. Simultaneous or previous evolution of chronic lymphocyttic thyroiditis into malignant lymphoma was confirmed in the papers of numerous authors. The authors presented a patient aged 58 in whom malignant lymphoma had evolved from the chronic diffuse lymphocytic thyroiditis. Cellular characteristics pointed to lymphoma of transformed cells being extended extrathyroidically into the surrounding connecting and muscular tissue with the involvement of regional lymph glands. Of particular importance was the area in which the usual architectonics of lymphocytic thyroiditis was discretely ruined and the infiltrate received neoplastic characteristics. On the basis of data from literature, lymphocytic thyroiditis should be regarded as a prelymphomatous state which was attached a great importance from the aspect of histopathologic analysis. Beside the operation, conservative therapy was employed and it showed good results until now, although it was too early to make decisive conclusions on the outcome of disease.