Dens of Axis Metastasis from Medullary Thyroid Cancer

Abstract

In 1997, a 45-yr-old female Caucasian underwent thyroidectomy with systematic lymph node dissection for a 2.5-cm large node-negative left medullary thyroid cancer (MTC). Basal calcitonin fell from 132 to 4.6 pg/ml but later climbed to 92.1 pg/ml (in 1999) and 335 pg/ml (2005). F-Dihydroxyphenylalanine (DOPA) positron emission tomography (PET), which is superior to F-fluorodeoxyglucose PET in MTC (1), revealed a 1-cm large paratracheal mass without distant metastases. Reoperation confirmed tumor invasion of the left laryngotracheal angle, anterior tracheal wall, and cricoid. A wedge resection was performed, and a sternocleidomastoid muscle flap was fashioned to cover the tracheal defect. Postoperative serum calcitonin was 176 pg/ml (2005) and 169 pg/ml (2006), with a magnetic resonance image showing scar tissue only before calcitonin started rising. F-DOPA PET (2008) and bone scintigraphy (2010) failed to spot the tumor. In 2011, basal calcitonin peaked at 648.6 pg/ml. On Gallium-DOTATOC, where DOTA is tetraazacyclododecane tetra aacetic acid and TOC is D-Phe-c(Cys-Tyr-D-TrpLys-Thr-Cys)-Thr(ol), PET-computed tomography (CT), an 8-mm large somatostatin receptor-positive, poorly demarcated osteoblastic tumor emerged in the left dens of axis, most likelyrepresentingmetastasis fromMTC(Fig.1).Falsepositive findings due to inflammation are theoretically possible with Gallium-DOTATOC but were considered highly unlikely. There was no evidence of other metastases. The lesion received 60 Gy of irradiation, and serum calcitonin decreased to 464 pg/ml, providing further support that the lesion represented metastatic MTC. DOTATOC is used for diagnostic and therapeutic purposes. Experience with Y-DOTATOC in MTC concentrating DOTATOC is limited to 12–21 patients: 0–10% achieved remission and 42–57% stable disease, whereas 33–58% sustained disease progression (2, 3). The effectiveness of Lu-DOTATOC (4) for MTC is unclear.