Multiple Endocrine Neoplasia (MEN)

Question 1

Define

Answer 1

DEFINITION: an autosomal dominant condition characterised by a predilection to develop tumours of endocrine glands.

Question 2

Causes

Answer 2

Autosomal dominant inheritance

Patterns of features:

MEN 1

• Pituitary adenomas
• Parathyroid tumours
• Pancreatic islet-cell tumours (and other endocrine tumours of the gastroenterohepatic tract e.g. gastrinomas)
• Fascial angiofibromas and collagenomas

MEN 2a

• Parathyroid tumours
• Medullary thyroid cancer
• Phaeochromocytomas

MEN 2b

• Same as MEN 2a
• Marfanoid appearance
• Neuromas of the GI tract

Question 3

Epidemiology

Answer 3

VERY RARE

Question 4

Symptoms

Answer 4

MEN 1

• Age of onset of tumours is usually teenage years
• However, symptoms of the tumours may not become apparent for years
• Diagnosis is commonly made in the 4th decade of life
• Symptoms and signs are dependent on the organs affects:
  
  • Hyperparathyroidism –> symptoms of hypercalcaemia + nephrolithiasis
  • Hypergastrinaemia –> Zollinger-Ellison syndrome
  • Hyperinsulinaemia –> hypoglycaemia
  • Hyperprolactinaemia –> amenorrhoea
  • Hypersomatotrophinaemia –> acromegaly
• Pituitary tumours may cause visual defects

MEN 2

• Symptoms of medullary thyroid cancer, hyperparathyroidism or phaeochromocytoma
• Medullary thyroid cancer symptoms:
  
  • Hypertension
  • Episodic sweating
  • Diarrhoea
  • Pruritic skin lesions
  • Lump in the neck
• Hypercalcaemia symptoms:
  
  • Constipation
  • Polyuria/polydipsia
  • Depression
  • Kidney stones
  • Fatigue

Question 5

Investigations

Answer 5

MEN 1

• Screening first or second degree relatives
• Hormone hypersecretion blood tests
• DNA testing

MEN 2

• Phaeochromocytoma test - 24 hr urine metanephrines
  
  • Can be followed by abdominal MRI
• Medullary thyroid cancer test - elevated calcitonin concentration
  
  • Can also be investigated with ultrasound and FNA
• Parathyroid tumours - simultaneously elevated Ca2+ and PTH