IgG4-Related Disease of the Thyroid Gland Requiring Emergent Total Thyroidectomy: A Case Report

Abstract

IgG4-related disease of the thyroid gland is a recently recognized subtype of thyroiditis, often with rapid progression requiring surgical treatment. It is considered as a spectrum of disease varying from early IgG4-related Hashimoto's thyroiditis (HT) pattern to late fibrosing HT or Riedel's thyroiditis patterns. Here, we report a 47-year-old Malay woman presenting with progressively painless neck swelling over 3 years and subclinical hypothyroidism. Computed tomography (CT) scan revealed diffuse thyroid enlargement (up to 13 cm) with retrosternal extension and without regional lymphadenopathy. Fine needle aspiration of the thyroid showed a limited number of follicular epithelial cell groups with widespread Hurthle cell change and scanty background colloid, but no evidence of lymphocytosis. The cytologic features fell into the category of 'atypia of undetermined significance'. Subsequently, the patient developed hypercapnic respiratory failure secondary to extrinsic upper airway compression by the thyroid mass and underwent emergent total thyroidectomy. Histology of the thyroid showed diffuse dense lymphoplasmacytic infiltrate and fibrosis. Follicular cells exhibited reactive nuclear features and some Hurthle cell change. IgG4+ plasma cells were over 40/high power field while overall IgG4/IgG ratio was above 50%. The overall features suggest the diagnosis of IgG4-related disease of the thyroid gland in the form of IgG4-related HT. Post-surgery, the patient was found to have markedly elevated serum IgG4 concentration but PET/CT did not show significant increased fludeoxyglucose uptake in other areas. Her recovery was complicated by a ventilator-associated pneumonia with empyema, limiting early use of corticosteroids for treatment of IgG4-related disease.

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 al18 in which neck swelling without symptoms of thyroid dysfunction were observed. Indeed, Li et al1 found 39% (11/28) of IgG4-RHT cases to be associated with subclinical hypothyroidism.…”

Reshaping the Concept of Riedel’s Thyroiditis into the Larger Frame of IgG4-Related Disease (Spectrum of IgG4-Related Thyroid Disease)

“…Generally, in endocrine practice, fine needle aspiration is the first choice in different lesions at the thyroid after initial clinical and ultrasound detection regardless of the underlying pathological report [ 58 , 59 ]. Yet, in RT the procedure is not useful for diagnosis as pointed out by our sample-based analysis (which in some cases was not feasible at all due to “iron-hard” thyroid consistency) [ 45 , 46 , 49 , 51 ].…”

“…Some suggested that identifying a high level of serum IgG4 in one patient with Hashimoto’s thyroiditis represents an early predictor for developing its fibrotic variant [ 90 ]. Both, RT and the fibrotic variant of Hashimoto’s thyroiditis have been suggested to represent the end stage of a long progressive evolution, but typically a higher risk of non-thyroid IgG4-mediated fibrosis is reported in RT (as opposed to the other entity) [ 58 , 91 ].…”

Clinical differences between IgG4 Hashimoto’s thyroiditis and primary thyroid lymphoma

“…It is associated with subclinical hypothyroidism, which indicates that the disease course may progress more rapidly. IgG4 HT presents as goitre, and sometimes the thyroid enlarges rapidly, leading to compressive symptoms, which consequently results in a high rate of thyroidectomies as compared with non-IgG4 HT ( 5 , 6 , 19 ). They are more vulnerable to papillary thyroid carcinoma and may have worse clinical outcomes, including a larger tumour diameter and a higher percentage of lymph node metastasis ( 11 ).…”

“…In 2009, Li et al ( 2 ) first proposed dividing HT into IgG4 and non-IgG4 HT based on IgG4 and IgG immunohistochemical staining results in thyroid tissue and found that IgG4 HT had unique clinical, serological, sonographic, and histopathological features compared to non-IgG4 HT ( 3 , 4 ). IgG4 HT can present as goitre, and sometimes the thyroid would become enlarged rapidly, leading to compressive symptoms, possibly requiring surgical removal ( 5 , 6 ). With regard to thyroid function, IgG4 HT is associated with hypothyroidism ( 3 ).…”