RESUMO
INTRODUCTION: Riedel´s thyroiditis is a thyroid inflammation with invasive fibrosis. CASE REPORT: Female 84 years old, studied by dysphagia to liquids and dysphonia, with cervical mass poorly demarcated and immobile. Computed Tomography (CT) (CT) showed tumor that diverted the trachea and esophagus compressed. Fine Needle Aspiration (FNA) obtained cells with atypia. Thyroidectomy was performed, appreciating a stony tumor which included the right recurrent laryngeal nerve. Given the high suspicion of thyroid malignancy tracheostomy it was performed. The pathology report as fibrosing Riedel thyroiditis. DISCUSSION: This is the less common type of chronic thyroiditis. Etiology is unknown. The normal thyroid parenchyma is replaced by fibrous connective tissue. Clinically usually a hard mass, fast growing, why is confused with thyroid carcinoma and Hashimoto's thyroiditis. It´ss more common in women and is usually bilateral. The CT or MRI (Magnetic Resonance Imaging) help assess the extent. Puncturing the mass could give us the diagnosis but is often difficult. Treatment to relieve symptoms or rule out malignancy is surgery. The prognosis is usually good. CONCLUSIONS: Riedel´s thyroiditis is an entity with histopathologic diagnosis essential