Late liver metastasis of medullary thyroid cancer with low calcitonin levels - successfully cured by radiofrequency.

A 28-year-old female consulted in 1994 for a left thyroid nodule known for two years with documented progression. Left lobe resection was performed initially followed by total thyroidectomy without lymph node dissection in September 1994. Pathological examination concluded on unilateral 10 × 40 mm medullary thyroid carcinoma (MTC). RET mutation was negative. Basal and pentagastrin-stimulated CT levels had been normal from 1994 to 2008 when her CT level was found to be elevated at 33 ng/L and increased subsequently to 111 ng/L in 2010. In accordance with guidelines, cervical ultrasound was performed repeatedly with negative results. After discussion in a multidisciplinary meeting and with patient's consent, an F-Dopa PET scan was proposed in disagreement with guidelines. This scan showed unique uptake in liver segment VI, which was confirmed by MRI. CT levels reached to 253 ng/L when she finally accepted treatment. In February 2013 we performed radiofrequency ablation of the lesion, which allowed normalisation of CT levels. This observation highlights the possibility of late recurrence of MTC. We could propose that for MTC patients with low-calcitonin levels-recurrences F-DOPA-PET/CT is a good diagnostic tool to use in case of repeatedly negative US neck studies. (Endokrynol Pol 2016; 67 (3): 326-329).