A 54-year-old man comes to the physician for evaluation of a thyroid nodule found on routine physical examination. He has no current complaints. His past medical history is significant for long-standing hypertension, hyperlipidemia, and glucose intolerance without overt diabetes mellitus. The patient's medications include amlodipine, simvastatin, and low-dose aspirin. He has no family history of thyroid disease or cancer.
Ultrasound reveals a 2-cm nodule in the right thyroid lobe. Fine-needle aspiration findings are consistent with medullary thyroid cancer. MRI of the neck shows no local extension or lymph node involvement.
Laboratory results are as follows:

Plasma fractionated metanephrines are within normal range.
Which of the following is the best next step in managing this patient?

Question

A 54-year-old man comes to the physician for evaluation of a thyroid nodule found on routine physical examination.  He has no current complaints.  His past medical history is significant for long-standing hypertension, hyperlipidemia, and glucose intolerance without overt diabetes mellitus.  The patient's medications include amlodipine, simvastatin, and low-dose aspirin.  He has no family history of thyroid disease or cancer.
Ultrasound reveals a 2-cm nodule in the right thyroid lobe.  Fine-needle aspiration findings are consistent with medullary thyroid cancer.  MRI of the neck shows no local extension or lymph node involvement.
Laboratory results are as follows:

Plasma fractionated metanephrines are within normal range.
Which of the following is the best next step in managing this patient?

Quizplus · Accepted Answer

11ec193a_97be_6ebf_853d_2f430808d3ef_MD0002_00 When medullary thyroid cancer is diagnosed, evaluation should focus on the following 3 entities: Evaluation for metastatic diseaseIdentifying co-existing tumorsIdentifying possible germline RET mutations Evaluation for metastatic disease Identifying co-existing tumors Identifying possible germline RET mutations The patient's normal serum calcium and plasma fractionated metanephrines make co-existing hyperparathyroidism and pheochromocytoma unlikely. Medullary carcinoma can spread to local lymph nodes or cause metastasis. Serum calcitonin levels correlate well with the metastatic disease burden. Therefore, the preoperative evaluation of medullary thyroid cancer (MTC) depends on serum calcitonin levels and presence of local lymph nodes. This patient has no local lymphadenopathy on MRI of the neck. Staging with CT of chest and upper abdomen is indicated when local lymph nodes are present and/or serum calcitonin is > 400 (Choice A). Triphasic bone scan is indicated only when skeletal metastasis is suspected (Choice E). The American Thyroid Association recommends germline RET mutation testing in all patients with newly diagnosed medullary thyroid cancer. Although 80% of MTC cases are sporadic, some patients with sporadic disease have germline RET mutations and thus have inheritable disease. All 3 MEN2 syndromes are inherited in an autosomal dominant fashion. RET mutation testing is helpful in defining prognosis and occurrence of other endocrinopathies in MEN2 patients. Moreover, if RET mutation analysis is positive, testing of first-degree relatives becomes important. (Choice C) Somatic RAS mutations are seen in some follicular thyroid cancers and follicular variant papillary thyroid cancers. (Choice D) Only thyroid follicular cells produce thyroglobulin, making it an excellent tumor marker for differentiated epithelial thyroid cancer. MTC arises from parafollicular C-cells, which do not produce thyroglobulin. Educational objective: Germline RET gene mutation testing is recommended in all patients with medullary thyroid cancer. Preoperative imaging of the neck, chest, and upper abdomen is performed when the local lymph nodes are present or serum calcitonin is > 400. __________ References: Medullary thyroid cancer: management guidelines of the American Thyroid Association. (http://www.ncbi.nlm.nih.gov/pubmed/19469690)

A 54-Year-Old Man Comes to the Physician for Evaluation of a Thyroid