Endocrine Abstracts

Introduction: Medullary thyroid carcinoma (MTC) is an aggressive neuroendocrine tumor derived from C cells that is responsible for approximately 5% of the gland malignancies, most of them occuring sporadically. Lymph node metastasis may occur early in disease pathogenesis and is one of the most important negative prognostic factor. Surgery is the only curative therapy while other chemotherapeutic options are limited. Neuroendocrine differentiated C cells may express somatostatin receptors (SSTR) and somatostatin analogs have been used with variable therapeutic success in cases of advanced MTC.

Case description: We present the case of a 56-year-old male patient who underwent total thyroidectomy for MTC. He was admitted in our clinic for a anterior neck mass. Thyroid ultrasonographic examination demonstrated a hypoechogenic 25/23/37.5 mm sized nodule invading the left thyroid lobe with microcalcifications. Laboratory work-up revealed an elevated calcitonin, greater than 2000 pg/ml (normal range<14.3), carcinoembryonic antigen (CEA) of 139.79 ng/ml (normal range: 0-2.5) and normal thyroid function. Our patient underwent a total thyroidectomy with total neck disection. Histological and immunohistochemical studies diagnosed the presence of multifocal MTC (pT2 mN1b) and papillary thyroid microcarcinoma (pT1aN0). The lymph nodes specimen showed metastases from the first lesion (six lymph nodes). The Ki-67 index was <1% and at the investigation for multiple endocrine neoplasia (MEN), RET protooncogene mutation was negative. Since CEA and calcitonin levels were high during follow-up period, neck ultrasonography was performed, with no evidence of pathologic lymphadenopathy, Cervical CT scan revealed a paratracheal left mass. Immunohistochemistry showed positive expression of somatostatin receptors (SSTR) 2 and 5 and the therapy with Octreotide LAR 30 mg every 4 weeks was initiated. An octreotide scan was performed with no detection of metastatic lesions. Six months later, under therapy with octreotide, calcitonins, CEA, serotonin, neuron specific enolase were within the normal range. The therapy was well tolerated with no side-effects recorded.

Conclusions: MTC can be a rare source of carcinoid syndrome. Some studies have shown that long-term octreotide and octreotide-LAR treatment offer a subjective and biological partial remission in one third and in one fourth of the MTC patients, respectively, but it does not improve the natural course of the tumor.

References: Vainas I et al, Somatostatin receptor expression in vivo and response to somatostatin analog therapy with or without other antineoplastic treatments in advanced medullary thyroid carcinoma. J Exp Clin Cancer Res. 2004 Dec;23(4):549-59. PMID: 15743023.