Introduction. Well-differentiated thyroid cancer (DTC) is curable in most patients with adequate surgical approach, radioactive iodine (RAI) treatment, and thyroid-stimulating hormone (TSH) suppression. However, around 2%-4% of cases experience a local recurrence in lateral cervical lymph nodes during a follow-up. Among these cases, nearly two-thirds become resistant to RAI therapy, known as RAI-refractory DTC (RR-DTC), offering poor prognosis and limited therapeutic options. We present the case of erroneously suspected RAI-refractory DTC due to incidental finding of coexisting cervical ganglioneuroma.
Case report. A 44-year-old man was administered the second radioiodine dose in our department due to the existence of locoregional metastatic lymph nodes of papillary thyroid carcinoma (PTC). During the follow up, raising tendency of suppressed serum thyroglobulin levels, negative control diagnostic ¹³¹I whole body scan, and negative ¹⁸F-fluorodeoxyglucose (FDG)-positron emission tomography scan (PET) aroused suspicion of RR-DTC. Although the patient was considered for peptide-receptor radionuclide therapy (PRRT) optionally, mainly because of positive finding in patient’s neck on ^99mTc-Hynic-TOC imaging (tektrotyd scan), the preference was given to a surgical approach. Finally, histopathological examination of extirpated neck tumor mass confirmed the presence of one lymph node metastasis of papillary carcinoma and coexistence of ganglioneuroma.
Conclusion. The authors want to point out the importance of multidisciplinary approach in diagnostics and therapy in case of suspected loss of thyroid differentiation features, as well as clinical awareness of coexisting asymptomatic rare tumors.

 Keywords: RAI therapy, RAI-refractory thyroid carcinoma, ganglioneuroma

 

Corresponding author:

Vesna D. Ignjatović

e-mail: vesnaivladaignjatovic@gmail.com