A rare association of two endocrine tumours: non-functional oncocytic adrenocortical carcinoma and Papillary thyroid carcinoma.

Objectives: To describe a rare association of two endocrine tumours in a clinical case.
Case Presentation: A 54-year-old woman with a classic Papillary thyroid cancer (PTC) assessed by the Endocrinology Department of a tertiary hospital from May-2015 to May-2020. PTC was treated with a total thyroidectomy and lymphadenectomy in May-2015. Initial staging (AJCC/TNM 7th edition): T3N1bMx. Additionally, two ablative doses of 150 mCi of 131-I (RAI) were administered until September-2016. No pathological uptake was found on the post-RAI whole-body scan at any level. Due to a persistent incomplete biochemical response in February-2017, a ¹⁸ Fluor-dexosiglucose positron emission computed tomography (FDG-PET) was performed. FDG-PET showed an intense pathological deposit in the right adrenal, suggestive of malignancy. Right adrenalectomy was carried out, and pathology revealed an Adrenocortical carcinoma (ACC). Genetic syndromes associated to ACC are: Li-Fraumeni syndrome (caused by an autosomal mutation in the TP53 gene), the Multiple Endocrine Neoplasia (MEN) type 1 (caused by Menin gene mutations), and MEN type 4 (caused by heterozygous mutations in the CDNK1B gene). However, none of them are associated to PTC.
Conclusions: To our knowledge this is the sixth published case reporting an ACC in presence of a PTC. The pathological factors behind the relation between these malignancies have not been elucidated. We do not discard the possibility of a genetic relationship between PTC and ACC.
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