---
title: "Medullary Thyroid Cancer"
description: "ENT notes on Medullary Thyroid Cancer - Risk factors, Clinical Features, Histology, Investigations and Treatment."
source: "The ENT Resident"
author: "Dr. Mausumi Das"
canonical_url: "https://www.theentresident.com/ent-notes-lectures/medullary-thyroid-cancer"
categories: ["Thyroid"]
video: "https://www.youtube.com/watch?v=xMPx7Tx4T-Y"
image: "https://media.theentresident.com/og-images/medullary-thyroid-cancer.png"
---

# Medullary Thyroid Cancer

ENT notes on Medullary Thyroid Cancer - Risk factors, Clinical Features, Histology, Investigations and Treatment. Watch the full video lecture on YouTube: https://www.youtube.com/watch?v=xMPx7Tx4T-Y

## 🦠 Medullary Thyroid Carcinoma (MTC)

- Accounts for **~5% of all thyroid malignancies**

- Constitutes **5–10% of pediatric thyroid cancers**

- Unlike other thyroid cancers, Medullary Thyroid Carcinoma **does NOT arise from follicular cells**.

- **Male : Female ≈ 1 : 1**

> What is the most common type of Thyroid cancer?

> What cells does Medullary Thyroid Carcinoma originate from?

> Which Thyroid cancer has female preponderance?

---

### 🧠 Classification of Medullary Thyroid Carcinoma

**1️⃣ Sporadic Medullary Thyroid Carcinoma**

- Most common type
- Age: **4th–6th decade**
- **Unifocal**
- No associated endocrinopathy

**2️⃣ Familial Medullary Thyroid Carcinoma**

- **Multifocal**

- **Bilateral**

Familial MTC is further divided into:

| Type | Frequency | Age of onset |
| --- | --- | --- |
| **MEN 2A** | >50% | 2nd–3rd decade |
| **MEN 2B** | ~5% | 1st–2nd decade |
| **FMTC** | Least common | 4th–5th decade |

> Which is the most common type of Medullary Thyroid Carcinoma?

> What type of inheritance pattern is seen in Familial Medullary Thyroid Carcinoma?

---

### 🧠 MEN Syndromes & Medullary Thyroid Carcinoma

#### MEN 2A (Sipple Syndrome)

🚩 **Mnemonic: 1M + 2P**

- **M** → Medullary thyroid carcinoma
- **P** → Pheochromocytoma
- **P** → Parathyroid hyperplasia (adenoma most common)

Other associations:
- Hirschsprung disease (rare)
- Cutaneous lichen amyloidosis (interscapular region)

#### MEN 2B (Most aggressive)

🚩 **Mnemonic: 3M + 1P**

- **M** → Medullary thyroid carcinoma
- **M** → Mucosal ganglioneuromas (tongue, lips, conjunctiva, GIT)
- **M** → Marfanoid habitus
- **P** → Pheochromocytoma

Other features:
- Enlarged lips
- Thickened corneal nerves
- Skeletal abnormalities (pectus excavatum, pes cavus, joint laxity)

> What mutations are seen in MEN2A & MEN2B?

---

### 🩺 Clinical Features of Medullary Thyroid Carcinoma

**Local Features**

- **Painless thyroid nodule** (>75%)
- Later:
  - Dysphagia
  - Hoarseness
  - Dyspnea
  - Pain

**Metastasis (Common at Diagnosis)**

- **Cervical nodes**: 40–50%

- Distant (hematogenous):
  - Liver
  - Lung
  - Bone
  - Brain
  - Skin

**Hormonal Effects**

- ↑ **Calcitonin** → diarrhea, flushing
- Rare:
  - ACTH / CRH secretion → **Cushing syndrome** (poor prognosis)

---

### 🔬 Pathology of Medullary Thyroid Carcinoma

**Gross**

- Solitary or multifocal
- Usually **non-encapsulated**
- Upper 2/3 of thyroid
- Less than 1 cm → **Medullary microcarcinoma** (better prognosis)

**Microscopy**

- Tumor cells:
  - Round to polygonal
  - Arranged in **solid, trabecular, insular, or nested patterns**
- **Fibrocollagenous stroma**
- **Amyloid deposition**

> 🔑 **Only thyroid cancer associated with amyloidosis**

> Why does Amyloid deposition occur in Medullary Thyroid Carcinoma?

> What does Congo red stain show in Medullary Thyroid Carcinoma?
---

### 🔍 Investigations of Medullary Thyroid Carcinoma

- Ultrasound neck
- FNAC (amyloid is diagnostic)
- **Serum calcitonin** 
- **CEA**
- Serum calcium (MEN 2A)
- Plasma / urine metanephrines (pheochromocytoma)

> ⚠️ Always rule out pheochromocytoma **before thyroid surgery**

> Why should you always rule out pheochromocytoma **before thyroid surgery**?

> Which is the most sensitive biochemical marker of Medullary Thyroid Carcinoma?

---

### 🛠️ Treatment of Medullary Thyroid Carcinoma

**Primary Treatment**

- Total thyroidectomy
- Central compartment (Level VI ± VII) neck dissection

> When is Lateral Neck Dissection indicated in Medullary Thyroid Carcinoma?


**Distant Metastasis**

- Surgery for airway / esophageal protection

- External beam radiotherapy

- Targeted therapy:
  - **Vandetanib**
  - **Cabozantinib**

---

### 🧪 Follow-Up of Medullary Thyroid Carcinoma

- Lifelong follow-up

> What are the parameters that should be monitored in a case of Medullary Thyroid Carcinoma?

> How long does it take for Calcitonin to normalize in Medullary Thyroid Carcinoma postoperatively?

---

### 🛡️ Prophylactic Thyroidectomy (RET-positive) in Medullary Thyroid Carcinoma

| Mutation | Timing |
| --- | --- |
| Codon 918 / 883 | < 1 year (preferably < 6 months) |
| Codon 634 | By 5 years (earlier if calcitonin > 40 pg/mL) |
| Other mutations | Delayed, monitor calcitonin |

---

### 📊 Prognosis of Medullary Thyroid Carcinoma

- 10-year survival: **56-96%**

- Biochemical cure → **97.7% survival**

- Children: **95% 5 year survival**

> What is Calcitonin / CEA Doubling Time? What value has a good prognosis and bad prognosis?

---

### 📌 Exam Pearls

- Only thyroid cancer from **C cells**
- Only thyroid cancer with **amyloid**
- Calcitonin = diagnostic + prognostic marker
- MEN 2B = **most aggressive**
- Rule out pheochromocytoma **before surgery**

---

## About This Note

This free ENT note on Medullary Thyroid Cancer was written by Dr. Mausumi Das and is paired with a corresponding video lecture.

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