Thyroid Neoplasms

“CLASSIFICATION”

Benign: follicular adenoma

Malignant:

       
1. Primary-

        a. Follicular epithelium ( differentiated)

            Follicular

            Papillary

        b. Follicular epithelium (undifferentiated)

            Anaplastic

        c. Parafollicular cells

            Medullary

        d. Lymphoid cells

            Lymphoma

        
2. Secondary

            Metastatic        

Papillary Carcinoma

a. Epidemiology

    Accounts for 80% of malignant thyroid tumors.

    F>M ; Age 20-50

    Risk factor: radiaton exposure

b. Micro

    exhibits a papillary pattern.

    psammoma bodies present.

    characteristic nuclear features:

       clear “Orphan Annie eye” nuclei.

       nuclear grooves.

       intranuclear cytoplasmic inclusions.

c. Lymphatic spread to cervical nodes is commom.

d. Treatment: Resection is curative in most cases.

                      Radiotherapy with iodine 131 is effective for metastases.

e. Prognosis: excellent

Follicular carcinoma

     

a. Accounts for 15% of malignant thyroid tumors

     

b. Females> males; age 40-60

     

c. Hematogenous metastasis to the bones or lungs is common

Medullary carcinoma

     

a. Accounts for 5% of malignant thyroid tumors

     

b. Arises from C cells (parafollicular cells) and secretes    calcitonin

     

c. Micro: nests of polygonal cells in an amyloid stroma

    

d. Minority (25%) are associated with MEN II and MEN III syndromes

Anaplastic carcinoma

a. Presentation

i. Females> males; age >60

ii. Firm, enlarging, bulky mass

iii. Dyspnea and dysphagia

iv. Tendency for early widespread metastasis and invasion of the trachea and esophagus

          

b. Micro: undifferentiated, anaplastic, and pleomorphic cells

         

c. Prognosis: very aggressiveand rapidly fatal

Surgical terms:

Lobectomy: complete removal of one lobe including isthmus.

Near total thyroidectomy: Total lobectomy with isthmusectomy with subtotal lobectomy.

Subtotal thyroidectomy: isthmusectomy with subtotal lobectomy b/l

Total thyroidectomyb/l lobectomy with isthmusectomy.

Management of thyroid cancers

Papillary Ca. thyroid surgery:

• Node negative, <1cm---lobectomy
• >1cm----Total thyroidectomy
• Evidence of spread present----Total thyroidectomy
• Familial disease---Total thyroidectomy
• Neck irradiation in childhood---Total thyroidectomy

Follicular Ca. surgery

Minimal capsular invasion, <1cm---lobectomy
Vascular invasion---Total thyroidectomy

Anaplastic Ca.

Surgery rarely indicated.

L/N surgery

Neck surgery