Aggressive Synchronous Papillary and Likely Follicular Thyroid Carcinomas in a Patient with Graves' Disease

We report a case of an uncommonly aggressive presentation of the rare entity of synchronous papillary (PTC) and follicular thyroid carcinomas (FTC) in a 67-year-old female initially presenting with thyrotoxicosis from Graves' disease. She was found to have two thyroid nodules with extensive intra-cardiac tumour thrombus, symptomatic left pelvis bony metastasis with pathological fracture, pulmonary metastases and mediastinal lymph node metastases. Further investigations suggested a diagnosis of synchronous papillary and metastatic follicular thyroid cancer. Treatment with radical surgery followed by adjuvant therapeutic radioiodine ablation was proposed, but the patient declined all forms of cancer-specific therapy and was elected solely for a palliative approach to treatment. We discuss the diagnostic considerations in arriving at the diagnosis of synchronous thyroid malignancy - in this case the clear features of PTC and the strong probability of FTC due to invasiveness and metastatic follicular lesions. This case underscores potential limitations of the ACR TI-RADS system, notably with certain ultrasonographic features suggesting malignancy that might not be adequately captured. Notably, the aggressive presentation of DTC in this case may be contributed by the concurrent presence of Graves' Disease, suggesting heightened vigilance when assessing potential thyroid malignancies in such patients.