Thyroid tumors

Dr. Gehan Mohamed

Classification of thyroid tumors

• A- benign tumors: more common than malignant thyroid neoplasm.

e.g follicular thyroid adenoma

B- Malignant thyroid tumors.

Criteria for diagnosis of follicular adenoma

• 1- solitary nodule

• 2- encapsulated

• 3- presence of compressed thyroid tissue outside capsule of thyroid adenoma.

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

Normal Thyroid

colloid

Thyroid epithelial cells

T4 90%

T3 10%

TSH

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

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

When suspect malignancy in thyroid mass

• 1-Male sex

• 2- Solitary thyroid nodules in patients >60 or <30 years of age

• 3-Large Nodules (>3 or 4 cm) with rapid Growth

• 4-Symptoms especially a change in voice,Pain,dysphagia,Stridor,hemoptysis

Molecular Level

• Medullary Carcinoma• Mutation in RET gene

• Papillary Carcinoma• Mutated RET, RAS, or BRAF gene

Typical Presentation of Thyroid Cancer

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

Papillary Carcinoma

•Most common type

•Females outnumber males 3:1– Highest incidence in women in midlife.

•Lymph node involvement is common Major route of metastasis is lymphatic

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

• <5% of patients have distant metastases at time of

diagnosis

– Lung is most common site

Thyroid carcinoma

Micropapillary thyroid carcinomas

Definition - papillary carcinoma smaller

than 1.0 cm

Most are found incidentally at autopsy

Usually clinically silent

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 .

Papillary carcinoma of thyroid

Papillary Thyroid Cancer: nuclei are oval or elongated, pale staining with ground glass

appearance

Follicular variant of papillary carcinoma

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

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.

Invasive follicular carcinoma:malignant follicles invade pink fibrous capsule

Follicular thyroid carcinoma

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 High power magnification

Hürthle Cell Tumor

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

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

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

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.

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

Medullary Thyroid CancerMetastases

• Cervical lymph node metastases occur early

• Tumors >1.5 cm are likely to metastasize,

often to bone, lungs, liver, and the central

nervous system

• Metastases usually contain calcitonin and

stain for amyloid

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

Physical Exam (continued…)

• Examine for ectopic thyroid tissue

• Indirect or fiberoptic laryngoscopy

vocal cord mobility

evaluate airway

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

Ultrasonography (Continued…)

• Disadvantages Cannot accurately distinguish benign

from malignant nodules