FDG PET/CT Negative Medullary Thyroid Carcinoma Patient with Elevated CEA Level: Case Report and Review of Literature

Abstract

ecurrent or metastatic medullary thyroid carcinoma (MTC) is usually presents with high calcitonin and carcinoembryonic antigen (CEA) as well. There is some several case reports in the literature incidentally firstly recognized with Fluorine-18 Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography (F-18 FDG PET/CT) with suspicion of elevated CEA levels with metachronous colon carcinoma.1, 2 Elevated tumor markers (calcitonin and CEA) usually refer to either metastasis or recurrence in patients with MTC. There are several imaging methods in identification of recurrence or metastasis in these kinds of patients which are conventional morphological imaging methods which do not yield a high In some circumstances imaging of thorax or whole body imaging may be necessary in these patients in the follow up. Calcitonin levels in combination with carcinoembryonic antigen is markers that we use in the follow up of MTC patients which elevation indicates recurrence and the recurrence cite may be described by means of Fluorine-18 Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography (F-18 FDG PET/CT) imaging which was negative in our case. In this case we report a patient with exceptionally high carcinoembryonic antigen (CEA) and low calcitonin level in one month postoperative follow up who was diagnosed as having false positive CEA elevation and discuss the diagnostic methods and tumor markers in detection of the Medullary Thyroid carcinoma.K Ke ey yw wo or rd ds s: : Fluorodeoxyglucose F18; positron-emission tomography; carcinoembryonic antigen; thyroid cancer, medullary; calcitonin Ö ÖZ ZE ET T Tümör göstergeleri medüller tiroid karsinomu hastalarında diğer ultrasonografi gibi görün-tüleme metodlarına ek olarak güvenilir olduğu kabul edilerek kullanılmaktadır. Bazı durumlarda bu hastalarda takipte toraks ve tüm vücut görüntüleme de gerekli olabilir. Kalsitonin ve karsinoembriyonik antijen birlikte medüller tiroid karsinomu takibinde güvenilir olarak kullanılır ve yüksel-meleri nüksü gösterir ve rekürrens alanı F-18 FDG PET/BT gibi tetkiklerle tanımlanabilir ki bizim hastamızda bu negatif idi. Biz bu vaka ile nadiren görülen düşük kalsitonin düzeyine karşılık yük-sek karsinoembriyonik antijen yüksekliği ile tanı alan yanlış CEA pozitifliğini raporluyor ve medüller tiroid karsinomunda tanısal metodlar ile tümör göstergelerinin yerini tartışıyoruz.A An na ah ht ta ar r K Ke el li im me el le er r: : Fluorodeoksiglukoz F18; pozitron emisyon tomografi;