A 30 year old female patient complains of painless hard anterior neck mass. FNAC was inconclusive. Open thyroid biopsy was performed which revealed the  ﬁbrous nature of the mass, woody, non tender thyroid, mimicking carcinoma is  observed.  The diagnosis points towards
De Quervain's thyroiditis Riedel's thyroiditis Hashimoto’s thyroiditis None of the above