The Thyroid

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The Thyroid Powered By Docstoc
					The Thyroid
Goals and Objectives


• Review thyroid anatomy and function
• Present sweet case
• Discuss pathology related to sweet case
Anatomy 101
Closer…
Closer still…




          • Too close
Not quite as close…
Thyroid Function in Review
Key Players
• TRH
   – From parvocellular neurons of hypothalamus
• TSH
   – From basophilic cells of anterior pituitary
• Thyroglobulin
   – Stores T1-T4 in colloid
• T4
   – More common
   – More potent
• T3
   – More common
   – More potent
• Calcitonin
Normal Thyroid
When good thyroids go bad

      • Hypofunctioning
      • Hyperfunctioning
      • Neoplasia
The Case
1950s
What can’t be radiated?
• Therapeutic irradiation
  –   Acne
  –   Excessive facial hair
  –   Tuberculosis of the neck
  –   Fungal diseases of the scalp
  –   Sore throat
  –   Chronic cough
  –   Enlargement of thymus, tonsils, adenoids
2002
• CC: neck mass, fatigue
• TSH 0.42, free T4 1.1
  138 102 15             8.5
                        94
   3.7 28 1.0

• FNA
  – benign colloid goiter
2003
• Breast cancer (left)
  – Surgical resection
    • Adenocarcinoma
    • ER/PR positive
  – Chemotherapy
    • Faslodex
    • Zometa
• CT-chest…
2005
• CT-chest
  – Large heterogeneous mass at thoracic
    inlet with tracheal deviation to the left
  – Innumerable lung nodules (2mm-
    1.5cm)
  – Rib lesion…
    • Metastatic adenocarcinoma (ER/PR+)
2005
• Thyroid U/S
  – Right lobe, 5.8x3.6x8.6cm
    • Superior nodule, 5.2x2.9x3.8cm
    • Inferior nodule, 4.9x3.8x5.3cm
  – Isthmus
    • Nodule, 4.6x2.2x6.9cm
  – Left lobe, 2.2x1.9x5.3cm
    • Lower, 1.6x1.6x1.6cm
    • Mid, 0.9x1.0x0.9cm
2005
• FNA
 – Right lobe
   • Upper: benign colloid goiter
   • Lower: benign colloid goiter
 – Isthmus
   • Benign colloid goiter
 – Left lobe
   • Lower: benign colloid goiter
   • Mid: papillary carcinoma
2006
• CC: fatigue, dry skin
• Neck mass enlarging
• TSH 0.11, free T4 4.4, free T3 5.9
• Thyroglobulin 292.8 [3-40]
• CT-chest/abd/pelvis
  – Thoracic inlet mass has neck extension
• CT-neck…
2006
• CT-neck
  – 9.0x6.4x7.9cm, poorly defined mass
  – Tracheal compression and invasion
• Subtotal thyroidectomy…
2006
• Subtotal thyroidectomy
  – Papillary carcinoma, T4aNxMx
• Thyroid body scan
  – Thyroid uptake 14%
  – No visible mets, but sensitivity decreased
     • Remaining thyroid tissue
     • Normal TSH
• 29 mCi I 131 delivered
• Levothyroxine started
2007
• Thyroid body scan
  – Thyroid uptake 4%
  – Diffuse lung mets
• 143 mCi I 131 delivered
• Thyroid body scan
  – Thyroid uptake 1.6%
  – Lung uptake 15%
  – Left femur/hip lesion?
• 75 mCi I 131 delivered
• TSH 4.92 (0.69), Thyroglobulin 175.0 (108.4)
2008 and Beyond
• ???
Thyroid Cancer
The Types
              Thyroglobulin   Calcitonin

 Papillary       Positive      Negative


 Follicular      Positive      Negative


 Medullary      Negative       Positive


 Anaplastic     Negative       Negative
Papillary
Follicular
Medullary
Anaplastic
Risk Factors
• Radiation
  –   Low- or high-dose
  –   40-50 Gy
  –   Ionizing radiation
  –   X-ray
  –   Radiotherapy
• Iodine deficiency
• Family history?
What’s a Gy?
• Gray
• 1975: Louis Harold Gray
  (1905-1965)
• Absorption of one joule
  of radiation energy by
  one kilogram of matter
• 100 rad
How much is 40-50 Gy?
• 10-20 Gy at once = fatal
• Abdominal x-ray = 1.4 mGy
• CT-abd/pelvis = 30 mGy
• 1000m from Nagasaki = 9-10 Gy
Epidemiology
•   1.5% of all cancers worldwide
•   Mean survival 90% at 10 years
•   70% papillary
•   10-15% present with lymph node or lung mets
•   Female predominance
     – Age > 45 = 2.8:1
Presentation
• Common          • Rare
 – Asymptomatic     – Pain
   mass             – Stridor
 – Cough            – Vocal cord
 – Dypsnea            paralysis
 – Dysphagia        – Rapid enlargement
Pathophysiology
• trk proto-oncogene
  – Tyrosine kinase
• ret proto-oncogene
  – “Rearranged during transfection”
Lab work
•   T4
•   T3
•   TSH
•   Thyroglobulin
•   Calcium
•   Calcitonin
•   CEA
•   TSH suppression test
Other Investigations
• Plain films, CT, MRI
• Echography
• Scintography
• FNAB
Histology
• Orphan Annie eyes
• Psammoma bodies
Staging
• Less than 45             • Over 45
   – Stage I                 – Stage I
      • Any T, any N, M0         • T1, N0, M0

   – Stage II                – Stage II
                                 • T2, N0, M0
      • Any T, any N, M1
                                 • T3, N0, M0
                             – Stage III
                                 • T4, N0, M0
                                 • Any T, N1, M0
                             – Stage IV
                                 • Any T, any N, M1
Treatment
• Surgical resection
   – Lobectomy
   – Subtotal thyroidectomy
   – Total thyroidectomy
• Radioablation
   – Non-metastatic: 30-100 mCi q3wk
   – Metastatic: 150-200 mCi q3wk
• External beam radiation
• Thyroid replacement
• Chemotherapy
   – Cisplatin
   – Doxorubicin
Summary
• Number of iodine molecules in the most
  metabolically active thyroid hormone?
  – Three
• Most common thyroid cancer?
  – Papillary
• Greatest risk for thyroid cancer?
  – Radiation exposure
• Treatment for thyroid cancer?
  – Resection and radioablation
The End

				
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posted:8/11/2012
language:English
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