IgG4-related Hashimoto’s thyroiditis – A new variant of a well known disease

Abstract

SUMMARYHashimoto's thyroiditis (HT) has been characterized for many years as a well-defined clinicopathologic entity, but is now considered a heterogeneous disease. IgG4-related HT is a new subtype characterized by thyroid inflammation rich in IgG4-positive plasma cells and marked fibrosis. It may be part of the systemic IgG4-related disease. We report a case of a 56-year-old Portuguese man who presented with a one-month history of progressive neck swelling and dysphagia. Laboratory testing revealed increased inflammatory parameters, subclinical hypothyroidism and very high levels of thyroid autoantibodies. Cervical ultrasound (US) demonstrated an enlarged and heterogeneous thyroid gland and two hypoechoic nodules. US-guided fine needle aspiration cytology was consistent with lymphocytic thyroiditis. The patient was submitted to total thyroidectomy and microscopic examination identified typical findings of HT, marked fibrosis limited within the thyroid capsule and lymphoplasmacytic infiltration, with > 50 IgG4-positive plasma cells per high-power field and an IgG4/ IgG ratio of > 40%. After surgery, serum IgG4 concentration was high-normal. Symptoms relief and reduction in laboratory inflammatory parameters were noticed. Thyroid function is controlled with levothyroxine. To our knowledge we report the first case of IgG4-related HT in a non-Asian patient. We also perform a review of the literature regarding IgG4-related disease and IgG4-related HT. Our case highlights this new variant of the well known HT, and helps physicians in recognizing its main clinical features, allowing for proper diagnosis and treatment. Arq Bras Endocrinol Metab. 2014;58(8):862-8 SUMÁRIO A tireoidite de Hashimoto (TH) foi caracterizada durante muitos anos como uma entidade clinicopatológica bem definida, mas é atualmente considerada uma patologia heterogênea. A TH associada a IgG4 apresenta-se como um novo subtipo, sendo caracterizada por inflamação da tireoide com numerosos plasmócitos IgG4-positivos e fibrose extensa. É possível que pertença ao espectro da doença sistêmica associada a IgG4. Relatamos o caso de um homem português de 56 anos que se apresentou com aumento progressivo do volume cervical e disfagia, com um mês de evolução. A avaliação laboratorial revelou elevação dos parâmetros inflamatórios, hipotireoidismo subclínico e níveis muito elevados de autoanticorpos tireoidianos. Por ultrassonografia cervical demonstrou-se tireoide aumentada, heterogênea, com dois nódulos hipoecoicos. Foi realizada citologia aspirativa com agulha fina guiada por ultrassom, compatível com tireoidite linfocítica. O doente foi submetido à tireoidectomia total e o exame histológico revelou achados típicos de TH, extensa fibrose localizada dentro da cápsula tireoidiana e infiltrado linfoplasmocitário, com > 50 plasmócitos IgG4-positivos por campo de grande ampliação e uma relação IgG4/IgG > 40%. Após cirurgia, a concentração sérica de IgG4 encontrava-se no limite superior do normal. Ocorreu melhoria sintomática e redução dos parâmetros inflamatór...

IgG4‐positive extranodal marginal zone lymphoma arising in Hashimoto's thyroiditis: clinicopathological and cytogenetic features of a hitherto undescribed condition

“…The cytological findings of IgG4 thyroiditis are poorly documented, with rare reports in the literature describing features of lymphocytic thyroiditis, without additional details. 10,11 The cytological features in our case corroborate the histological findings. The prominent microfollicular distribution with Hurthle cell change may result in a false diagnosis of Hurthle cell neoplasm, as illustrated in our case.…”

“…The cytological findings of IgG4 thyroiditis are poorly documented, with rare reports in the literature describing features of lymphocytic thyroiditis, without additional details . The cytological features in our case corroborate the histological findings.…”

Review of IgG4-related Hashimoto Thyroiditis With Best Practice Recommendations for Diagnosis and Reporting

“…Our patient's symptoms due to mass effect (dysphagia, airway obstruction) rather than chemical insult (eg, heat or cold intolerance, tremors, changes in energy level, etc.) align with reports of Luiz et al, 14 Kang et al, 16 and Zhao et al 18 in which neck swelling without symptoms of thyroid dysfunction were observed. Indeed, Li et al 1 found 39% (11/28) of IgG4-RHT cases to be associated with subclinical hypothyroidism.…”

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