Riedel's Thyroiditis Mimicking as Anaplastic Thyroid Carcinoma: Unusual Presentation.

Riedel's thyroiditis is a rare inflammatory process which not only involves thyroid gland but also the surrounding vital structures. It may also be associated with various forms of systemic fibrotic disorders. The exact etiology is not known, but currently most favored view is that of a localized form of systemic fibrotic process. We report a case of Riedel's thyroiditis in a patient, highlighting a rare presentation mimicking anaplastic carcinoma. Clinical awareness of such presentation of Riedel's thyroiditis would enhance our ability to make this diagnosis promptly. Apart from avoiding or minimizing aggressive surgical intervention, awareness of such clinical entity may avoid complications and hence morbidity. Our case also highlights the difficulty in histological diagnosis which is very important to rule out malignancy and avoiding any major surgical intervention fraught with complications. Good response to high dose steroids as seen in our case is the current accepted treatment of choice.