A 22-year-old man comes to the office for evaluation of a neck mass. He first noticed a small nodule in his lower neck 6 months ago, and it has progressively enlarged since that time. The patient has had no changes in weight and otherwise feels well. Medical history is notable only for seasonal allergies, and he takes no medications. Physical examination shows a 2-cm nodule in the right lobe of the thyroid. There are multiple 4- to 8-mm soft papules on the lips and tongue. The arm span exceeds his height and the patient has long fingers. Serum calcitonin levels are elevated. Which of the following is most likely to develop in this patient?

Question

A 22-year-old man comes to the office for evaluation of a neck mass.  He first noticed a small nodule in his lower neck 6 months ago, and it has progressively enlarged since that time.  The patient has had no changes in weight and otherwise feels well.  Medical history is notable only for seasonal allergies, and he takes no medications.  Physical examination shows a 2-cm nodule in the right lobe of the thyroid.  There are multiple 4- to 8-mm soft papules on the lips and tongue.  The arm span exceeds his height and the patient has long fingers.  Serum calcitonin levels are elevated.  Which of the following is most likely to develop in this patient?

Quizplus · Accepted Answer

11ec160b_3ac6_2c05_9249_e3c289852aa1_MD0001_00 This patient has an enlarging thyroid nodule associated with an elevated calcitonin level, which is concerning for medullary thyroid cancer (MTC), a malignancy arising from the thyroid C (parafollicular) cells. These findings, in association with mucosal neuromas and marfanoid habitus (eg, arm span > height, long fingers, joint laxity), suggest multiple endocrine neoplasia type 2B (MEN2B). MEN2 syndromes are caused by germline mutations of the RET proto-oncogene. MTC is present in nearly all patients with MEN2 and is usually more aggressive and occurs at an earlier age than sporadic MTC. Pheochromocytomas develop in roughly half of patients with MEN2 syndromes and cause paroxysmal hypertension and tachycardia due to the intermittent secretion of catecholamines. The abrupt, severe increase in blood pressure can precipitate episodic headaches and is often accompanied by other symptoms associated with catecholamine excess (eg, diaphoresis, tremor, chest pain). (Choice B) Hyperparathyroidism with secondary hypercalcemia is the most common manifestation of MEN1. Hyperparathyroidism (due to parathyroid chief cell hyperplasia or adenoma formation) is also seen in 10%-20% of patients with MEN2A, but it is not a feature of MEN2B. (Choices C and E) Many patients with MEN1 have endocrine pancreatic tumors that secrete gastrin, leading to refractory peptic ulceration and diarrhea (Zollinger-Ellison syndrome). In rare cases, endocrine tumors of the pancreas in MEN1 secrete other hormones, such as insulin, which can cause hypoglycemia. (Choice D) Pituitary tumors are present in 50% of patients with MEN1. Large pituitary tumors with suprasellar extensions are likely to cause peripheral vision loss. Educational objective: Multiple endocrine neoplasia type 2B is characterized by medullary thyroid cancer, pheochromocytomas, mucosal neuromas, and marfanoid habitus. Hyperparathyroidism is not a feature of this syndrome. __________ References: 2012 European Thyroid Association guidelines for genetic testing and its clinical consequences in medullary thyroid cancer. (http://www.ncbi.nlm.nih.gov/pubmed/24783025) Revised American Thyroid Association guidelines for the management of medullary thyroid carcinoma. (http://www.ncbi.nlm.nih.gov/pubmed/25810047)

A 22-Year-Old Man Comes to the Office for Evaluation of a Neck