Thyroid tumors

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Thyroid tumors

• Dr. Gehan Mohamed

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Classification of thyroid tumors

• A- benign tumors more common than malignant
  thyroid neoplasm.
• e.g follicular thyroid adenoma
• B- Malignant thyroid tumors.

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Criteria for diagnosis of follicular adenoma

• 1- solitary nodule
• 2- encapsulated
• 3- presence of compressed thyroid tissue outside
  capsule of thyroid adenoma.

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Classification of Malignant Thyroid Neoplasms

• Papillary carcinoma
• Follicular variant
• Tall cell
• Diffuse sclerosing
• Encapsulated
• Follicular carcinoma
• Overtly invasive
• Minimally invasive
• Hurthle cell carcinoma
• Anaplastic carcinoma
• Giant cell
• Small cell

• Medullary Carcinoma
• Miscellaneous
• Sarcoma
• Lymphoma
• Squamous cell carcinoma
• Mucoepidermoid carcinoma
• Clear cell tumors
• Plasma cell tumors
• Metastatic
• Direct extention
• Kidney
• Colon
• Melanoma

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Normal Thyroid
TSH
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Types of Thyroid Cancer

• Papillary (80-85) develops from thyroid
  follicle cells in 1 or both lobes grows slowly
  but can spread
• Follicular (5-10) common in countries with
  insufficient iodine consumption lymph node
  metastases are uncommon
• Medullary develops from C-cells, can spread
  quickly sporadic .
• Anaplastic develops from existing papillary or
  follicular cancers aggressive, usually fatal
• Lymphoma develops from lymphocytes uncommon

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Risk Factors for development of thyroid carcinoma

• Radiation
• High dose x-rays of the neck or face during
  infancy or teenage years is a risk factor
  specially for papillary carcinoma
• Family History
• Goiters and prolonged TSH stimulation is a risk
  for follicular carcinoma.
• Mutated RET oncogene
• Gender
• males

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When suspect malignancy in thyroid mass

• 1-Male sex
• 2- Solitary thyroid nodules in patients gt60 or
  lt30 years of age
• 3-Large Nodules (gt3 or 4 cm) with rapid Growth
• 4-Symptoms especially a change in
  voice,Pain,dysphagia,Stridor,hemoptysis

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Molecular Level

• Medullary Carcinoma
• Mutation in RET gene
• Papillary Carcinoma
• Mutated RET, RAS, or BRAF gene

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Typical Presentation of Thyroid Cancer

• Painless lump
• Normal thyroid function tests
• Found on routine examination or by the patient

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Papillary Carcinoma

• Most common type
• Females outnumber males 31
• Highest incidence in women in midlife.
• Lymph node involvement is common
• Major route of metastasis is lymphatic

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Papillary Thyroid CancerCharacteristics

• Unencapsulated tumor nodule with ill-defined
  margins
• Tumor typically firm and solid
• First presentation of the patient may be lymph
  node enlargment.
• Commonly metastasizes to neck and mediastinal
  lymph nodes
• 40 to 60 in adults and 90 in children
• lt5 of patients have distant metastases at time
  of diagnosis
• Lung is most common site

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Thyroid carcinoma
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Micropapillary thyroid carcinomas

• Definition - papillary carcinoma smaller than 1.0
  cm
• Most are found incidentally at autopsy
• Usually clinically silent

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Papillary Carcinoma(continued)

• Pathology
• Gross - vary considerably in size
• - often multi-focal
• - unencapsulated but often have a
  pseudocapsule which is normal thyroid tissue
  compressed by the tumor mass.
• Histopathology - closely packed papillae which
  have fibrovascular core.
• - psammoma bodies which is a
  laminated calcification
• - nuclei are oval or elongated, pale
  staining with ground glass appearance .

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Papillary carcinoma of thyroid
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Papillary Thyroid Cancer nuclei are oval or
elongated, pale staining with ground glass
appearance
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Follicular variant of papillary carcinoma
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2- Follicular Thyroid Carcinoma

• Second most common type of thyroid cancer
• Solid invasive tumors, usually solitary and
  encapsulated
• Usually stays in the thyroid gland, but can
  spread to the bones, lungs, and central nervous
  system.
• Usually does not spread to the lymph nodes

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Follicular Carcinoma

• Pathology
• Gross - encapsulated, solitary
• Histology - very well-differentiated.
  (distinction between follicular adenoma and
  follicular carcinoma is so difficult so we
  depend on presence of vascular and capsular
  invasion to diagnose follicular carcinoma.

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Invasive follicular carcinomamalignant
follicles invade pink fibrous capsule
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Follicular thyroid carcinoma
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Hürthle Cell Carcinoma

• A variant of follicular cancer that tends to be
  aggressive
• Microscope there are Large, polygonal,
  eosinophilic thyroid follicular cells with
  abundant granular cytoplasm and numerous
  mitochondria

Hürthle Cell Tumor
High power magnification
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Hürthle Cell tumor

• May be benign or malignant, based on
  demonstration of vascular or capsular invasion
• Malignancies tend to have a worse prognosis than
  other follicular tumors
• Tend to be locally invasive

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3- Anaplastic Thyroid Cancer

• Often occurs in the elderly population (mean age
  65 years)
• Three fold greater risk in iodine-deficient areas
• Tumor is typically hard, poorly circumscribed,
  and fixed to surrounding structures.
• Extremely aggressive and exceptionally virulent

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Anaplastic Carcinoma of the Thyroid

• Pathology
• Classified as
• Composed wholly or in part of
  undifferentiated cells which may be large cell or
  small cell
• Large cell is more common and has a worse
  prognosis
• Histology - sheets of very poorly differentiated
  cells
• little cytoplasm
• numerous mitoses
• necrosis
• extrathyroidal invasion

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Medullary Thyroid Carcinoma

• Tumor arising from the calcitonin-secreting
  C-cells of the thyroid gland.
• Developes in 3 clinical settings
• Sporadic MTC (SMTC)
• Familial MTC (FMTC)
• Multiple endocrine neoplasia.

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Medullary Thyroid Carcinoma characterized by
presence of pink amyloid in between malignant
cells.
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Medullary Thyroid CancerMetastases

• Cervical lymph node metastases occur early
• Tumors gt1.5 cm are likely to metastasize, often
  to bone, lungs, liver, and the central nervous
  system
• Metastases usually contain calcitonin and stain
  for amyloid

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Evaluation of any thyroid Nodule(Physical Exam)

• Examination of the thyroid nodule
• consistency - hard vs. soft
• size more than 4.0 cm
• Multinodular vs. solitary nodule
• multi nodular 3 chance of malignancy
• solitary nodule 5-12 chance of malignancy

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Physical Exam (continued)

• Examine for ectopic thyroid tissue
• Indirect or fiberoptic laryngoscopy
• vocal cord mobility
• evaluate airway

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Evaluation of the Thyroid Nodule

• Advantages of Ultrasonography
• Noninvasive and inexpensive
• Most sensitive procedure or identifying lesions
  in the thyroid (can detect smaller lesions even
  2-3mm size)
• 90 accuracy in categorizing nodules as solid,
  cystic, or mixed
• Best method of determining the volume of a nodule
  
• Can detect the presence of lymph node enlargement
  and calcifications

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Ultrasonography (Continued)

• Disadvantages
• Cannot accurately distinguish benign from
  malignant nodules