6. Multiple Endocrine Neoplasia (MEN)

Question 1

Definition of Multiple Endocrine Neoplasia Syndromes

Answer 1

Group of genetically inherited AD diseases resulting in proliferative lesions (hyperplasia, adenoma, carcinoma) of multiple endocrine organs

Question 2

Genetic associations of MEN 1 (Wermer syndrome)

Answer 2

MEN1 tumour suppressor gene (encodes menin)

Question 3

Common lesions of MEN 1

Answer 3

1. Parathyroid
   - Hyperplasia or adenoma
   - Results in hyperparathyroidism
2. Pancreas
   - Endocrine neoplasms (especially insulinomas & gastrinomas)
3. Pituitary
   - Prolactinomas (most common), growth hormone secreting tumours

Question 4

Genetic associations of MEN2a (Sipple syndrome)

Answer 4

RET protooncogene (gain of function mutation)

Question 5

Common lesions of MEN2a (Sipple syndrome)

Answer 5

1. Parathyroid
   - Hyperplasia
2. Pheochromocytoma
3. Thyroid medullary carcinoma
   - Almost always associated with background of parafollicular cell hyperplasia

Question 6

Genetic associations of MEN2b

Answer 6

RET protooncogene (single amino acid change distinct from the alterations seen in MEN IIa)

Question 7

Common lesions of MEN2b

Answer 7

1. Mucocutaneous neuromas
   - Involves skin, eyes, respiratory tract & GIT
2. Pheochromocytoma
3. Thyroid medullary carcinoma
   - Almost always associated with background of parafollicular cell hyperplasia