Hashimoto's thyroiditis manifesting monoclonal lymphocytic infiltration

Abstract

SUMMARYHashimoto's ihyroiditis (HT) and lymphoma are sometimes diffieult to distinguish belween. Moreover, lymphoma sometimes develops in a thyroid gland from pre-existing HT. Ofien-or largeneedlc biopsy usually distinguishes between ihem; the specimen may be examined hislotogically and subjected to immunohislochcmlslry. Another possible method of examination is finc-nccdie aspiration hiopsy (FNAB). The cells obtained may be evaluated cylologically, and subjected lo flow cytometry. using various antibodies. In this study, anti-kappa and anti-lambda antibodies are especially important, as a gross predominance of kappa or lambda B lymphocytes infiliraiing the thyroid is evidence for a B cell moniKlone. In this sludy. 15 patients were selected bcxause of Iheir rapidly growing goitres. They all underwent FNAB. Five had cytology typical of HT, and no evidence of monoclonality on flow cyiomeiry. They were diagnosed as HT without further hisiopaihology. The remaining 10 patients had cytology suspected of lymphoma. or evidence of monoclonality on flow cylotiielry, or both. These patients underwent open-or largc-needlc biopsy. Only three of them were diagnosed hisiopaihologically as lymphoma; the other seven were diagnosed histopathologically asHT. making 12 cases of HT in all. Five of the.sc 12 cases, and one of the three cases of lymphoma showed flow cyiometrical evidence of monoclonality; thus evidence of monoclonality from FNAB, while interesting, does not necessarily serve to differentiate between HT and lymphoma. Furthermore, ihc immunohistochcmical assessment of monoclonalily did not correlate with the flow cytomelrical assessment. Follow-up evidence will be required lo discover whether those patients with a B cell monoclone in their HT are the ones who develop a lymphoma.

Epstein-Barr Virus and Autoimmunity

“…Thyrotoxicosis can develop immediately after infectious mononucleosis due to primary EBV infection, and autoimmune hypothyroidism can develop in association with acute EBV infection [59]. Intrathyroidal EBV-infected B cells could be the source of the monoclonally expanded B cells in the thyroid gland in autoimmune thyroiditis [60] and might be responsible for the increased risk of development of B-cell lymphoma in the thyroid gland in patients with autoimmune thyroiditis [61].…”

Fine Needle Cytology and Flow Cytometry in Hashimoto Thyroiditis and Primary Thyroid Lymphoma

“…Therefore, we thought that light chain imbalances in a relative small number of cells, which are not supported by heavy chain rearrangements, may occur in HT and should not be considered indicative of HT. This occurrence had already been described in HT [4,5,6], although the corresponding percentages were quite variable [4,5,6], depending also on the different technical procedures [4,5,6]. Conversely, in 2 of our TL FNC-FC cases [3], FC showed light chain restrictions in almost all the gated B-lymphocytes in 1 case and, paradoxically, light chain restrictions were not expressed in the other case in which the cytological features suggested high-grade non-Hodgkin lymphoma.…”

Cervical Lymphadenopathy Associated with Hashimoto’s Thyroiditis

“…HT cases displaying monoclonality have been reported. 21 In a study by Tani and Skoog, 22 ICC was used in conjunction with cytomorphology to evaluate fine needle aspirates from 18 patients with nodular lymphoid infiltrates of the thyroid. Cytomorphology could not differentiate between an inflammatory and neoplastic lymphoid infiltrate in 2 cases.…”