A 75 year old man with symptomatic multinodular goiter and Bethesda category 4 dominant nodule underwent total thyroidectomy and lymph node dissection. He was diagnosed with a pT3, N1b, MX, poorly differentiated thyroid carcinoma, with papillary, follicular, oncocytic and tall cell foci, and evidence of vascular invasion. Following surgery, radioactive iodine (RAI) (6GBQ) was administered. Stimulated thyroglobulin (Stim-Tg) was elevated with no radiological evidence of distant metastases. Over the following 3 to 4 years, he has required additional two doses of ablative RAI (6GBQ and 8GBQ) due to ongoing rise in Unstim-Tg levels. There was also evidence of new bony (sacrum, humerus, femur) and pancreatic metastases with histopathology from biopsy of pancreatic lesions showing metastatic thyroid carcinoma. The pancreatic lesions and sacral lesion showed good clinical and radiological response to external beam radiotherapy (EBRT).
Unfortunately, more recently, there has been a further rise in the Unstim-Tg, evidence of new liver metastases on FDG/PET and slow growth of the femoral lesion, but without any clinical manifestations. This raises the question of, the most appropriate course of management in this gentleman with slow progression of disease but remains asymptomatic; Tyrosine Kinase Inhibitor (TKI) therapy versus active surveillance and symptomatic management. With complete metabolic response of pancreatic lesion to local EBRT, he has avoided debilitating surgery and the potentially toxic side effects of TKI therapy, which can occur in up to 60% of patients.
This case emphasizes that, the natural history of non-medullary thyroid cancer, can be indolent and unpredictable; and metastases to intra-abdominal organs are rare1 2 and present unique challenges. Multimodality Imaging is the key in staging and management should be guided by clinical manifestations. Local therapies, such as EBRT to isolated bony metastases, remain useful and in the setting of oligo-metastatic bone disease, may be all that is needed.