Diagnostic Fine Needle Aspiration in a Case of Riedel's Thyroiditis

In Riedel’s thyroiditis, a rare chronic inflammatory disease of thyroid gland, fine needle aspirationis usually non-diagnostic because most often only follicular cells are obtained and not the fibrousmaterial characteristic of this type of thyroiditis. Therefore the diagnosis is often only establishedby histopathologic study of the surgically obtained biopsy. The illustrated case is a 46-year-oldfemale who presented with a firm, non-mobile thyroid nodule of the left lobe. Fine needle aspirationwas performed, demonstrating fragments of fibrous tissue and few inflammatory cells includingneutrophils and lymphocytes, findings that could be representative of Riedel’s thyroiditis. Frozensection examination during subsequent surgery and later histopathologic study confirmed thediagnosis. Fine needle aspiration of the thyroid, if successfully done, could be highly suggestive forRiedel’s thyroiditis.