Endocrine Abstracts

Introduction: Among all thyroid nodules 3 to 10% are Hürthle cell (HC) neoplasms classified as either HC adenomas or carcinomas. The presence of capsular or vascular invasion is indicative of a HC carcinoma whose incidence has been found to be 5 to 35%. Hürthle cell carcinoma could also lead to distant metastases and its decreased ability to uptake radioiodine worsens the prognosis. There are reports of histologically characterized HC adenomas with unpredictable clinical course. Here, we present a case of a HC ‘adenoma’ proved to be malignant 11 years post-thyroidectomy.

Case Presentation: A 73-year-old male presented at our department with a history of total thyroidectomy 11 years ago due to goiter with an 8.5 cm nodule on the left thyroid lobe. The histological examination revealed an atypical Hürthle cell adenoma. Consequently, he has been receiving levothyroxine substitution therapy but never pursued follow up by a specialized Endocrinologist. On October 2018 a chest CT was performed due to a pulmonary infection that revealed a 3.5 cm nodular lesion on the left lung. The FDG-PET CT scan that followed showed additional hypermetabolic loci on the left side of the neck. Biopsy was taken from the latter as well as from transbronchial needle aspiration and both displayed neoplastic infiltration with morphological and immunohistochemical characteristics of Hürthle cell thyroid carcinoma. Thyroglobulin levels exceeded 6000 ng/mL. Brain CT was negative. The following whole-body scan with radioiodine I-131 after recombinant thyrotropin stimulation showed radionucleotide uptake on thyroid tissue remnants, on the upper mediastinum and on the upper lobe of the left lung. The patient has been evaluated by a thoracic surgeon who characterized the condition as inoperable. Therefore, he received 150 mCi I-131. The post ablation WBS showed the majority of I-131uptake on the neck area and minor uptake on the lung. Hence, additional therapeutic strategies will be followed.

Conclusion: Even though histologically characterized Hürthle cell adenomas could be reassuring, long term follow up by a specialized Endocrinologist is essential in the context of occasional recurrence or metastases, leading in a final diagnosis of a Hürthle cell carcinoma as in our case.