Co-occurrence of Amyloid Goiter and Adipose Metaplasia in a Patient With History of Pulmonary Tuberculosis: A Case Report

Abstract

Amyloid goiter is described as an accumulation of amyloid, an amorphous proteinaceous material, in the thyroid gland. The deposition of amyloid is relatively common in the thyroid gland. However, a significant clinical enlargement due to amyloid accumulation and fat deposition in the thyroid stroma resulting in diffuse goiter leading to compressive symptoms is a rare phenomenon. In this report, we describe a rare case of amyloid goiter with adipose metaplasia in a 38-year-old woman with a history of pulmonary tuberculosis who presented to the outpatient department with complaints of heartburn, abdominal discomfort, and hoarseness of voice. Incidentally patient had diffused multinodular neck swelling. Preliminary blood investigations were normal. The contrast-enhanced computed tomography neck showed multiple non-enhancing lesions and a diffusely enlarged thyroid gland, causing a mass effect on the oropharynx posteriorly and minimally on the trachea. Fine needle aspiration cytology thyroid revealed thyroiditis. The patient underwent a total thyroidectomy, and histopathological examination of the specimen showed an extracellular eosinophilic amorphous substance that was positive for Congo red and showed apple-green birefringence under polarized light, and large areas of adipose metaplasia were noted, and a diagnosis was made. The amyloid involvement can result from localized primary deposition or secondary to chronic inflammatory disease. The prevalence of amyloid goiter in developed countries is due to primary amyloidosis, and in developing countries is due to secondary amyloidosis. Patients with a history of pulmonary tuberculosis commonly present with renal amyloidosis as its complication. Patients with an enlarged thyroid gland and a history of chronic inflammatory conditions or plasma cell dyscrasias should be evaluated with extreme suspicion. The correlation of tuberculosis with the subsequent development of amyloid goiter highlights the need for research in this area.

Keywords: adipose metaplasia; amyloid goiter; amyloidosis; chronic inflammatory disease; diffuse goiter; fine needle aspiration cytology (fnac); multinodular goiter; plasma cell dyscrasias; pulmonary tuberculosis; thyroidectomy.