Please help with the following topic for Surgery final year Mbbs exam. Give it in a short note form
Asking for Preferences
Multiple endocrine neoplasia
Reading File
Finding Sources
Searching the Web
Multiple endocrine neoplasia MEN1 MEN2 surgery MBBS short notes 2024
Reading File
Reading File
Reading File
I now have comprehensive content from Bailey & Love (Surgery), Robbins Basic Pathology, and Robbins Cotran Pathologic Basis of Disease. Let me compile the short note.
Multiple Endocrine Neoplasia (MEN) - Short Note
Definition
MEN is a group of autosomal dominant inherited disorders characterised by proliferative lesions (hyperplasias, adenomas, carcinomas) involving two or more endocrine glands. Tumours arise at a younger age, are multifocal, often bilateral, are preceded by hyperplasia, and are more aggressive than sporadic counterparts.
MEN 1 (Wermer's Syndrome)
Genetics:
- Mutation in MEN1 tumour suppressor gene on chromosome 11q13
- Encodes menin - a protein regulating transcription, cell division, and proliferation
- "Two-hit" mechanism: germline mutation + somatic second hit
- Prevalence: ~1 in 30,000
Mnemonic: "3 Ps"
| Gland | Lesion | Frequency | Notes |
|---|---|---|---|
| Parathyroid | Four-gland hyperplasia/adenoma | 95% | Most common & earliest manifestation; presents by age 40-50 |
| Pancreas | Islet cell (P-NET) tumours | 30-80% | Leading cause of death in MEN1 |
| Pituitary | Adenoma (mainly prolactinoma) | 15-50% | GH-secreting causes acromegaly |
Pancreatic tumours (in order of frequency):
- Gastrinoma (30%) → Zollinger-Ellison syndrome (recurrent peptic ulcers, diarrhoea)
- Non-functioning P-NETs (most common on screening - up to 70%)
- Insulinoma → hypoglycaemia
- Glucagonoma, VIPoma, Somatostatinoma (rare)
Other associations: Adrenocortical tumours (40-50%), carcinoid tumours (lung, thymus, stomach), lipomas, meningiomas, facial angiofibromas
MEN 2 (Sipple Syndrome - MEN 2A)
Genetics:
- Activating mutation in RET proto-oncogene on chromosome 10q11.2
- Unlike MEN1 (tumour suppressor), RET is an oncogene (gain-of-function mutation)
- Autosomal dominant
MEN 2A (Sipple Syndrome) - more common
| Component | Details |
|---|---|
| Medullary thyroid carcinoma (MTC) | ~100% of patients; bilateral, multicentric; secretes calcitonin; preceded by C-cell hyperplasia |
| Phaeochromocytoma | 50%; often bilateral; must be excluded before thyroid surgery |
| Primary hyperparathyroidism | 20-30%; milder than MEN1 |
MEN 2B - less common (~5% of MEN2)
| Component | Details |
|---|---|
| MTC | More aggressive, earlier onset |
| Phaeochromocytoma | Present |
| Mucosal neuromas | Lips, tongue, GI tract (distinguishing feature) |
| Marfanoid habitus | Tall, slender build, arachnodactyly |
| Ganglioneuromas | GI tract → constipation/diarrhoea |
| No hyperparathyroidism | Absent in MEN 2B |
Comparison Table
| Feature | MEN 1 | MEN 2A | MEN 2B |
|---|---|---|---|
| Gene | MEN1 (chr 11) | RET (chr 10) | RET (chr 10) |
| Gene type | Tumour suppressor | Proto-oncogene | Proto-oncogene |
| Parathyroid | Yes (95%) | Yes (20-30%) | No |
| Pancreas | Yes (30-80%) | No | No |
| Pituitary | Yes (15-50%) | No | No |
| MTC | No | Yes | Yes (aggressive) |
| Phaeochromocytoma | No | Yes (50%) | Yes |
| Neuromas/Marfanoid | No | No | Yes |
Key Surgical Points
- MEN 2 - Screen RET gene in all first-degree relatives; prophylactic thyroidectomy in RET mutation carriers (timing depends on RET codon mutation - highest risk: before age 6 months)
- Phaeochromocytoma must always be excluded before any surgery in MEN 2
- MEN 1 - PHPT treatment: subtotal (3.5 gland) parathyroidectomy or total parathyroidectomy + autotransplantation
- Gastrinoma in MEN1: PPIs to control symptoms; surgery for localised lesions; often multifocal/metastatic making cure difficult
- MTC marker: Calcitonin (diagnostic + follow-up); CEA also elevated
- Screening: Annual biochemical surveillance for all MEN1 mutation carriers from early adolescence
Exam High-Yield Points
- MEN1 = Wermer syndrome | MEN2A = Sipple syndrome
- RET mutation → MEN2 (oncogene) | Menin mutation → MEN1 (tumour suppressor)
- Most common MEN1 lesion = PHPT (95%)
- Leading cause of death in MEN1 = Pancreatic NET (metastatic)
- Most common pituitary tumour in MEN1 = Prolactinoma
- MEN2B distinguishing features = Mucosal neuromas + Marfanoid habitus (no parathyroid involvement)
- Calcitonin = tumour marker for MTC
- Always rule out phaeochromocytoma before thyroid surgery in MEN2
Sources: Bailey & Love's Short Practice of Surgery 28e, p.933 | Robbins & Kumar Basic Pathology | Robbins, Cotran & Kumar Pathologic Basis of Disease, p.1042
This is a shared conversation. Sign in to Orris to start your own chat.