Endocrine Abstracts

Introduction: Medullary thyroid carcinoma (MTC) is a neuroendocrine tumor that arises from the parafollicular C-cells of the thyroid gland with a tendency to regional and distant metastases. It is a rare tumor, making up about 3% of all thyroid malignancies. MTC occurs in both heritable and sporadic forms, early diagnosis is important as it can improve treatment outcomes. We report a case of metastatic medullary thyroid cancer with both diagnostic and therapeutic challenges.

Case presentation: 37-year-old man presented with anterior cervical mass. CT scan showed a cervico-mediastinal mass measuring 29 x 56 x 66 mm, with calcitonin level at 1890 ng/l. The patient underwent total thyroidectomy, with removal of the mediastinal mass and cervical lymph nodes. The pathology revelated initially a poorly differentiated malignant tumor proliferation of thymic origin. Immunohistochemistry was in favor of a neuroendocrine carcinoma. An anatomical-pathological re-reading revealed a medullary thyroid carcinoma aspect with secondary mediastinal location. One year later, the cervico-thoracic CT scan showed a retro clavicular mass of 31.3 mm x 26 mm x 20 mm, with intimate contact with the left common carotid artery, end intra-parenchymal micronodules measuring 4.4 mm and 4.2 mm, in favor of metastasis. The patient underwent an exeresis of the mass with surgical difficulty due to the intimate contact of the tumor with the cervical vascular axis. The patient was thereafter referred to medical oncology for systemic treatment.

Discussion: Distant metastases in MTC are observed at presentation in 7–23% of patients, they often affect multiple organs including lungs, bones and liver, and they are frequently associated with persistent disease in the neck. Calcitonin and carcinoembryonic antigen (CEA) with conventional radiographic modalities are widely used for the diagnosis, prognosis, and follow-up of MTC patients. In our case, the metastatic MTC was diagnosed with difficulty in the anatomo-pathological reading, with a loco-regional recurrence presenting a difficulty in the surgical management.

Conclusion: MTC is a rare disease with a high risk of not being cured by the initial treatment. In cases of metastasis, the approach depends on the severity and rate of progression of disease. Metastatic MTC can be treated with limited surgical resection, or medical management with tyrosine kinase inhibitors (TKIs) or another agent.