Endocrine Abstracts

Introduction: Medullary thyroid carcinoma (MTC) is a rare form of thyroid cancer, making up about 3–5% of all cases. It is characterized by the synthesis and secretion of calcitonin (Ct). Measurement of Ct has low specificity but is a highly sensitive method for the detection of MTC. MTC with normal or only slightly elevated Ct is a rare occurrence and there are few such reports in the literature.

Case report: A 61-year-old male patient was referred to the Endocrine consultation for evaluation of a solid, solitary, right lobe thyroid nodule, 38×30 mm in diameter. There were no suspiciously enlarged nodules on the neck sonogram. The nodule had fisrt been detected 2 years before and grew slowly since then. Fine needle aspiration (FNA) revealed a benign cytopathology. Serum TSH and FT4 were normal, with increased anti-peroxidase antibodies (826 IU/ml). Serum calcitonin was 15.4 ng/l and CEA was 2.4 μg/l. The patient underwent right lobectomy. Pathology analysis revealed MTC. There was no vascular nor capsular invasion. Immunohistochemistry was positive for synaptophysin and chromogranin A, and in very few cells for CEA and Ct. The frozen section specimens were sent to another Pathology Department of a public Oncology Hospital, which confirmed the diagnosis of MTC. Postoperative Ct level was <0.2 ng/l. Habitus marphanoid and mucosal neuromas were not apparent. Urinary cathecholamines and metanephrines were normal, as were serum calcium and PTH. There was no family history of endocrine disease. The results of the genetic testing of the RET gene are still pending.

Conclusions: The features of the sonogram and FNA test and the minimally increased level of Ct in the context of goiter and auto-immune thyroiditis did not raise suspicion of thyroid cancer. This is one of the rare cases described in the literature of MTC with almost normal Ct.