A 15-year-old boy comes to the office for evaluation of a neck mass. The patient first noticed the mass a month ago and it has progressively enlarged. He has had no neck pain, fever, or difficulty swallowing or breathing. Examination shows a firm, nontender mass affecting the left thyroid lobe. TSH is within normal limits. Ultrasonography reveals a hypoechoic 2-cm nodule in the upper portion of the left thyroid lobe. Fine-needle biopsy reveals a cluster of large cells with abundant cytoplasm that stain positive for calcitonin. The patient is also found to be positive for a germline RET mutation. A total thyroidectomy is planned. Prior to the surgery, additional testing should be performed to evaluate for an abnormality in which of the following organs?

Question

A 15-year-old boy comes to the office for evaluation of a neck mass.  The patient first noticed the mass a month ago and it has progressively enlarged.  He has had no neck pain, fever, or difficulty swallowing or breathing.  Examination shows a firm, nontender mass affecting the left thyroid lobe.  TSH is within normal limits.  Ultrasonography reveals a hypoechoic 2-cm nodule in the upper portion of the left thyroid lobe.  Fine-needle biopsy reveals a cluster of large cells with abundant cytoplasm that stain positive for calcitonin.  The patient is also found to be positive for a germline RET mutation.  A total thyroidectomy is planned.  Prior to the surgery, additional testing should be performed to evaluate for an abnormality in which of the following organs?

Quizplus · Accepted Answer

11ec160b_3ac7_3d77_9249_591c81348605_MD0001_00 This patient has medullary thyroid cancer (MTC), a neuroendocrine malignancy arising from the calcitonin-secreting parafollicular C cells. Most cases of MTC are sporadic, but approximately 20% are familial, due to germline mutations of the RET proto-oncogene. Multiple endocrine neoplasia type 2 (MEN2) is the most common inherited disorder associated with activating RET mutations, and is characterized by: Pheochromocytoma is a catecholamine-secreting neoplasm arising from the chromaffin cells of the adrenal medulla. Up to 50% of patients with MEN2 develop pheochromocytoma. In patients with undiagnosed pheochromocytoma, induction of anesthesia can precipitate a catecholamine (epinephrine and norepinephrine) surge, leading to hypertensive crisis, flash pulmonary edema, and atrial fibrillation. Therefore, patients who have MTC associated with germline RET mutations should be screened for pheochromocytoma (eg, 24-hour assay for urinary metanephrines and catecholamines) prior to surgery. (Choices A, C, D and E) MEN1 is characterized by anterior pituitary adenomas, primary hyperparathyroidism (due to parathyroid adenomas or hyperplasia), and neuroendocrine tumors of the pancreas and gastrointestinal tract (eg, gastrinoma, insulinoma). A number of other tumors are also more frequent in MEN1, including adrenocortical adenomas and neuroendocrine thymomas (thymic carcinoid). However, MEN1 is due to mutations in the MEN1 gene (not RET) and is not associated with MTC. Educational objective: Multiple endocrine neoplasia type 2 is caused by germline activating mutations in the RET proto-oncogene and frequently results in both medullary thyroid cancer and pheochromocytoma. In patients with undiagnosed pheochromocytoma, induction of anesthesia (eg, preparation for thyroidectomy) can precipitate a catecholamine surge, leading to hypertensive crisis, flash pulmonary edema, and atrial fibrillation. __________ References: The North American Neuroendocrine Tumor Society consensus guideline for the diagnosis and management of neuroendocrine tumors: pheochromocytoma, paraganglioma, and medullary thyroid cancer. (http://www.ncbi.nlm.nih.gov/pubmed/20664475)

A 15-Year-Old Boy Comes to the Office for Evaluation of a Neck