Primary thyroid diffuse large B-cell lymphoma: fine needle aspiration and histological correlation.

Primary thyroid lymphoma (PTL) is a rare type of cancer that arises within the thyroid gland, representing about 2%-8% of all thyroid malignancies. Fine-needle aspiration cytology is commonly used as the first-line diagnostic approach for thyroid nodules and can assist in identifying PTL when suggestive features are present. Herein, we report the case of a 59-year-old female patient who presented with a rapidly enlarging anterior neck mass over 20 days. Clinically, the case was challenging to distinguish from anaplastic thyroid carcinoma because of the sudden enlargement of the neck mass. However, pathological examination confirmed the diagnosis of primary thyroid diffuse large B-cell lymphoma. Fine-needle aspiration cytology proved valuable in avoiding unnecessary surgical resection and guiding appropriate treatment. Additionally, we provide a brief review of the clinical and cytopathological features of primary thyroid lymphomas.