Thyroid Neoplasms Flashcards
Name benign nodules of the thyroid
- cyst
- colloid nodule
- follicular nodule
- hyperplastic nodule
What percentage of nodules will be malignant?
5%
Who are follicular adenomas most common in?
Women >30 years old
Describe the histology of follicular adenomas
Discrete solitary mass. Composed of thyroid follicles & encapsulated by collagen
Are adenomas generally functional or non-functional?
Non-functional
When are adenomas most likely to be functional?
If there is a mutation involved in TSH signalling, increasing cAMP and therefore thyroid hormone production
What percentage of all cancers are thyroid cancers?
1.5%
Which gender is mainly affected by thyroid carcinoma?
Female
State the two cancers which are part of DTC
- papillary
- follicular
What hormone drives differentiated thyroid cancer?
TSH
What do most DTC take up and secrete?
Take up - iodine
Secrete - thyroglobulin
Describe the aetiology of DTC
Environment associations - ionising radiation and iodine deficiency
Genetic features
Where are mutations often found in papillary carcinomas?
MAP kinase pathway
Where are mutations often found in follicular carcinomas?
P13K/AKT pathway
Where are mutations often found in anaplastic carcinoma?
MAP kinase/P13K/AKT/p53/ beta catenine
What mutations are associated with medullary thyroid cancer?
Multiple endocrine neoplasm type 2
Describe the appearance of a papillary carcinoma
Usually a solitary nodule in the thyroid often cystic and may be calcified
What is the name given to the parts of a tumour that have calcified?
Psammoma bodies
What are the local effects of a papillary carcinoma?
Hoarseness, dysphagia, cough, dyspnoea
Where do papillary carcinomas usually spread to?
Lymphatics
If papillary carcinomas spread haematological where will it go to?
Lung
What disease is papillary carcinoma associated with?
Hashimoto’s thyroiditis
What is the 10 year survival of papillary carcinoma?
95%
What areas of the world have a higher incidence of follicular carcinoma?
Regions of iodine deficiency
If a follicular carcinoma is minimally invasive what will it look like?
Follicular architecture, may have surrounding capsule but difficult to distinguish from adenoma
If a follicular carcinoma is widely invasive what will it look like?
More solid architecture, less follicular and more mitotic
How do follicular carcinomas usually spread?
Haematogenous
What is the 10 year survival of follicular carcinoma?
Ranges from 50-100%
Where do medullary thyroid carcinomas arise from?
C cells that secrete calcitonin
Describe the aetiology of medullary thyroid carcinoma
Young patients - MEN
40-50 year olds - sporadic/familial
How will a sporadic MTC appear?
Solitary nodule
How will a familial MTC appear?
Multi-centric/bilateral due to C cell hyperplasia
Describe the histology of MTC
Composed of spindle/polygonal cells arranged in nests/trabeculae/follicles, necrosis, small cell morphology, often very aggressive
What is MTC often associated with?
Amyloid deposition - abnormal folded protein (calcitonin)
What is the typical presentation of an MTC?
Neck mass with local effects
What is the key risk associated with MTC?
Paraneoplastic syndrome
State the two checks that are important to determine the cause of MTC
- urinary metenephrines
- genetics
Describe anaplastic carcinoma
Undifferentiated aggressive tumours, usually in older patients with a history of DTC. Rapid growth, involvement of neck structures and death.
State two important questions in a suspected thyroid cancer history
- neck irradiation
- family history of thyroid cancer
What is the significance of the patient sticking out their tongue during examination?
Thyroglossal cyst will move - also will cause supra-hyoid midline swelling
What investigations should be carried out on a suspected solitary thyroid nodule?
TSH
Ultrasound +/- Fine needle aspiration
Describe the categories of USS FNA
Thy 1 - inadequate only blood cells seen Thy 2 - benign - U2 Thy 3 - atypical/follicular - U3 Thy 4 - probably malignant - U4 Thy 5 - malignant - U5
Who is a low risk group?
Age <50 years old, tumour<4cm
How are low risk groups managed?
Lobectomy - aim to keep TSH low and monitor baseline thyroglobulin
Who is a high risk group?
Palpable lymph nodes, >50 years old, >4cm tumour
How are high risk groups managed?
Total thyroidectomy - keep TSH low, monitor thyroglobulin, may need to use radio iodine
What do thyroglobulin levels help indicate?
Increases help to diagnose recurrent disease
State the T categories of TNM
T1 - = 2cm
T2 2-4cm
T3 - >4cm
T4a - any size extending beyond capsule within tracheal fascia
T4b - advanced disease involves pre vertebral fascia
State the N categories of TNM
N0 - no lymph nodes
N1a - regional lymph nodes
N1b - cervical/retropharyngeal/superior mediastinal lymph nodes
What condition is thyroid lymphoma associated with?
Hashimoto’s thyroiditis - B cell lymphoma
How does thyroid lymphoma present?
Rapidly expanding mass usually in women aged 70-80 years old
How is thyroid lymphoma diagnosed?
Core biopsy
What is the treatment for thyroid lymphoma?
Chemotherapy, radiotherapy, steroids
What are the investigations for a multi-nodular goitre?
Assess TSH
CT scan
What respiratory symptoms can a multi-nodular goitre cause and how can they be investigated?
Retrosternal extension/tracheal compression will cause stridor or choking when lying flat.
Volume loops can help identify the cause of respiratory symptoms
How are multi-nodular goitres managed?
Most can be left alone
Radioactive iodine if significant hyperthyroidism
Surgery if respiratory problems/cancerous/impacting life
What are the three types of surgery for thyroid nodules?
- thyroid lobectomy with isthmusectomy
- sub-total thyroidectomy
- total thyroidectomy
What risk assessment tool is used for risk stratification?
Age
Metastases
Extent of primary tumour
Size of primary tumour
Who is classed as a low risk?
Younger patients with no evidence of mets
Older patients with an intrathyroidal papillary lesion or minimally invasive follicular lesion where the primary tumour is <5cm with no distant mets
What is the 20 year survival for low risk patients?
99%
Who is classed as high risk?
All patients with distant mets, extra thyroidal disease in papillary carcinoma or significant capsular invasion in follicular carcinoma. Primary tumour >5cm
What is the 20 year survival for high risk patients?
61%
What surgery is used for AMES low risk patients?
Lobectomy and isthmusectomy
Describe a thyroid lobectomy and isthmusectomy
The gland is exposed 2-3cm above the sternal notch by separation of the strap muscles. The lobe is mobilised by diving the vessels supplying each part
Describe a sub/total thyroidectomy
?
What lymph node surgery is carried out in papillary tumours?
Central compartment clearance and lateral lymph node sampling
What lymph node surgery is carried out in follicular cancer?
Central node clearance
What should be checked within 24 hours of a thyroid operation?
Calcium - replacement initiated if levels are below 2mmol/l, if below 1.8 IV calcium is required
Name the investigation carried out usually 3-6 months post thyroid operation
Iodine scan
Describe the radio iodine scan
TSH >20 for best results
Monday/Tuesday - rhTSH injection
Wednesday - Iodine injection
Friday - Scan
What is the purpose of a radio iodine scan?
In order to view any residual thyroid tissue
If residual tissue is present on iodine scan what is done?
Thyroid remnant ablation
Describe thyroid remnant ablation
Patient is admired to a lead lined room with main sewage, pre-treated with rhTSH and 2-3 units of iodine are administered. Stay in the room until they are less radioactive (80% excreted in first 24 hours)
What is the aim of thyroid remnant ablation?
Suppress TSH and destroy remnant cells and mircofoci
What are the short and long term side effects of remnant ablation?
Short term - sialadenitis
Long term - increased incidence of AML
