Whole-body 18F-FDG PET/CT in primary non-Hodgkin’s lymphoma of the thyroid associated with Hashimoto’s thyroiditis

—An 82-year-old female patient with hypothyroidism and Hashimoto’s thyroiditis noted three years ago to have a small asymmetric goiter (left > right). Nevertheless, a rapid growth of the thyroid over 3-6 months caused dysphagia and shortness of breath. Ultrasound and a thyroid gammagram showed an image consistent with multinodular goiter with a hyperfunctioning nodule in the right lobe. Due to the history of Hashimoto’s thyroiditis and a rapid increase in size of the thyroid gland, diagnoses of thyroid lymphoma and anaplastic thyroid cancer were considered. Thyroidectomy was attempted at an outside facility to relieve compressive symptoms. Fine needle aspiration was insufficient for diagnosis, and the product of thyroidectomy confirmed the diagnosis of diffuse large B-cell lymphoma. A positron emission tomography/computed tomography scan was performed in our institution for staging, revealing nodal and extranodal metastasis. Chemotherapy using cyclophosphamide, vincristine and dexamethasone (COP modified) led to a dramatic response of the tumor and a complete resolution of compressive symptoms.