Backgroud: Distant metastases from papillary thyroid cancer (PTC) are infrequent and associated with poor prognosis. Adrenal metastatic lesions in this setting are rare, generally associated with lung and skeletal metastases. There have been few reported cases of isolated adrenal metastases from thyroid carcinoma. Here we report a patient with a PTC who developed a large and solitary adrenal metastasis.
Case Presentation: A 68-year-old men was submitted in 2015 to total thyroidectomy and left cervical lymphadenectomy due to a 48mm left thyroid nodule with a cytological diagnosis of PTC. The pathology revealed a classic and follicular variant of PTC with extensive angioinvasion and cervical lymph node metastases. He was submitted to treatment with 100mCi of radioactive iodine (RAI). Due to recurrent lymph node disease, in 2017 he underwent a right cervical lymph node dissection, followed by a second RAI treatment (100mCi). The whole-body scan performed 2 days after this treatment did not show any anomalous uptake. In 2018 a third surgery with left cervical lymph node dissection was performed. After that he showed no evidence of disease, with an undetectable level of thyroglobulin (Tg) and negative anti-thyroglobulin antibodies. Six years after the diagnosis (2021) the serum Tg increased from undetectable to 1758 ng/ml. A PET/TC-18FDG showed a single anomalous uptake at the left Thyroid (SUVmax of 15.4). A left adrenalectomy was then performed, revealing an adrenal metastasis (100x80x50mm) of poorly differentiated thyroid carcinoma, with solid and insular pattern. One month after surgery, Tg level dropped to 24 ng/ml. The patient is scheduled for a third RAI treatment.
Conclusions: This patient represents a very rare case of an initially well differentiated thyroid carcinoma with a single distant metastasis in the Thyroid which had a poorly differentiated pattern. This reinforce the importance of long-term surveillance with serum Tg levels.