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, the most favored view is that of a localized form of the systemic fibrotic process. We report a case of Riedel’s thyroiditis in a male patient, highlighting diagnostic challenges and a rare presentation of hypocalcemia and mimicking thyroid lymphoma. Clinical knowledge of such a presentation of Riedel’s thyroiditis would enhance our ability to make a speedy diagnosis. Apart from avoiding aggressive surgical intervention, awareness of such a clinical entity may avoid complications and hence morbidity. Our case also highlights the difficulty in histological diagnosis which is vital to rule out malignancy and avoiding any major surgical intervention fraught with complications. Although the patient had a poor tolerance to Tamoxifen and Rituximab, however, his response to high dose steroids is the currently accepted treatment of choice. This case adds to the sparse literature available on the cytological diagnosis of RT and highlights the diagnostic challenge due to suspicious radiology findings.© 2020 The Author(s).