Rosai–Dorfman disease of the thyroid presenting as a rapidly progressive airway-compromising mass mimicking anaplastic thyroid carcinoma: A case report

Background: Rosai–Dorfman–Destombes disease (RDD) is a rare histiocytic disorder with heterogeneous nodal and extranodal manifestations. Thyroid involvement is exceptional and may closely simulate aggressive thyroid malignancy. Case presentation: A 75-year-old woman presented with a rapidly enlarging, painful anterior cervical mass and dysphonia. Cervical ultrasonography demonstrated a multinodular goiter with a 7-cm right thyroid nodule classified as EU-TIRADS 4. Fine-needle aspiration was categorized as Bethesda V. Four days later, the patient developed acute upper-airway compromise; computed tomography showed approximately 80% tracheal luminal narrowing and pulmonary foci initially considered suspicious for secondary disease. Emergency surgical exploration was undertaken. Complete thyroidectomy was precluded by apparent common carotid artery involvement, and tumor debulking with tracheostomy was performed. Frozen-section examination showed eosinophilic tumor-like cells with malignant-appearing features but did not establish anaplastic thyroid carcinoma. Definitive histopathological examination and immunohistochemical assessment supported a non-Langerhans histiocytosis consistent with RDD. Corticosteroid therapy was initiated and the patient was referred for oncologic evaluation; she was subsequently lost to follow-up. Conclusion: Thyroid RDD may present as a rapidly progressive, locally aggressive, airway-threatening mass and can be cytologically and intraoperatively indistinguishable from anaplastic thyroid carcinoma. Definitive tissue assessment is essential before disease-specific oncologic treatment is instituted.