Excellent Objective Response to Lenvatinib in a Patient of Recurrent Radioiodine Refractory Poorly Differentiated Thyroid Carcinoma

Abstract We herein present a patient of recurrent radioiodine refractory poorly differentiated thyroid carcinoma (PDTC) with excellent response to lenvatinib in recurrent setting. The patient was a known case of PDTC, operated for primary followed by local radiotherapy to the neck. The patient presented with recurrence at 8 years' follow-up with left-sided supraclavicular neck swelling and elevated serum thyroglobulin levels. Biopsy from the supraclavicular nodal mass demonstrated metastasis in known case of PDTC. 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) done for disease extent evaluation, demonstrated two hypermetabolic large volume soft tissue density nodal masses in the left supraclavicular region and anterior mediastinum. The patient was administered lenvatinib with possible surgical intent as the disease was unresectable due to encasement of critical vessels (left common carotid artery). Four months into the therapy with lenvatinib, response evaluation 18F-FDG PET/CT showed excellent partial response, which lasted for a year, and the disease eventually progressed.