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  • • Family of syndromes including:

    • -MEN 2A (Sipple syndrome)

      -MEN 2B

      -Familial medullary thyroid carcinoma (FMTC)

    • MEN 2A is characterized by:

    • -Medullary thyroid carcinoma (MTC)

      -Pheochromocytomas

      -Parathyroid hyperplasia

    • MEN 2B consist of MTC, pheochromocytoma, mucosal neuromas, gangliomatosis of the GI tract, and a distinctive marfinoid habitus

    • -Also have high incidence of skeletal abnormalities, such as congenital dislocation of the hip, pes planus or cavus, kyphosis, and pectus excavatum

    • Transmitted as mendelian autosomal trait, but can occur de novo (especially MEN 2B)

    • Common mutation is in the Ret proto-oncogone (tyrosine kinase), which maps to the centromeric region of chromosome 10

    • Families with hereditary MTC need to be identified with an aggressive screening program because early diagnosis and thyroidectomy renders MTC curable in a large percentage of patients

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Epidemiology

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  • • MEN 2A and 2B are transmitted with 100% penetrance but variable expressivity

    • Nearly every affected person with MEN 2A and 2B develop bilateral, multicentric MTC

    • Pheochromocytomas are present in 50% of MEN 2A patients

    • Parathyroid hyperplasia is present in 25% of MEN 2A patients

    • MTC occurs earlier and is more aggressive in patients with MEN 2B than those with MEN 2A

    • 20% of MTC occurs in a familial setting

    • Peak incidence of MTC in setting of FMTC, MEN 2A, or MEN 2B is second or third decade of life

    • Pheochromocytomas appear in second or third decade of life; 60% are bilateral

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Symptoms and Signs

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  • • Diarrhea

    • Palpable thyroid nodule, or multinodular thyroid gland

    • Enlarged, firm cervical nodes (if metastatic disease)

    • Hoarseness, dysphagia

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Laboratory Findings

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  • • Calcitonin level is elevated (either basally, or after stimulation with calcium and pentagastrin)

    • Elevated plasma metanephrines; elevated urinary catecholamines

    • Elevated serum calcium and intact parathyroid hormone

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Imaging Findings

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  • Neck x-rays: May show irregular, dense calcifications

    Chest film: May show calcified metastatic hilar and mediastinal nodes

    Abdominal CT scan: Can demonstrate adrenal masses

    MIBG scan: Can localize pheochromocytomas

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  • • MTC is usually the first abnormality expressed in MEN 2A and 2B

    • Pheochromocytomas are nearly always limited to the adrenal medulla and are nearly always benign

    • Most patients are asymptomatic with respect to parathyroid disease

    • Pheochromocytoma should be excluded prior to operative neck exploration

    • Genetic testing is available for Ret mutations

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  • • Complete history (including family) and physical exam

    • Serum calcitonin, calcium, parathyroid hormone, metanephrine levels

    • Genetic screening for all patients with MTC

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Surgery

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Indications

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  • • Elevation of calcitonin level or as soon as diagnosis of FMTC, MEN 2A, or MEN 2B is made

    • Presence of pheochromocytoma

    • Hypercalcemia

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Treatment Monitoring

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  • • Calcitonin level

    • Routine radiologic and biochemical screening for pheochromocytoma

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