Thyroid Tumours - Approach

Classification:

1.Epithelial -

• Papillary
• Follicular
• Anaplastic (old patient, rapidly growing, no Rx, median survival 3-6/12)

2. "C" cells -

• Medullary (Sporadic, Familial, MEN II)

3. Others -

• Lymphoma
• Sarcoma
• Mets

* Well differentiated Thyroid CA:

Papillary

a. Standard

b. Solid variant (post irradiation)

c. Follicular variant


Follicular

a. Minimally invasive

b. Widely invasive


*Anaplastic

a. Squamoid variant

b. Small cell variant - can look like lymphoma, medullary Ca)



Poorly differentiated Ca

a. Tall cell

b. Insular cell

Invx & Mx

Careful hx paying attention to

1. Lump factors

2. Risk factors for Thyroid Ca (Radiation - occupational, Chernobyl, lymphoma RxT to thymus & FHx - medullary Ca)

3. Cx of Ca (RLN invasion, LN, SVC compression, retrosternal extension - stridor, fixity to str. - skin/strap muscles, haemoptysis, mets - lung, bone)

Biochemical assessment

• Thyroid functional status - Free T4 and TSH
• Thyroid Antibodies - anti-thyroglobulin and anti-microsomal
• If positive family history an possibility of medullary carcinoma - calcitonin
• If suspicion of MEN2 Syndrome will need 24 hr urinary catecholamine estimations to exclude phaeochromocytoma prior to surgery
  

Standard radiography
Chest radiography and thoracic inlet views if obstructive symptoms

Isotope scanning

• 131I , 123I or 99Tch scanning provides functional assessment of thyroid
• Nodules classified as cold, warm or hot
• Unable to differentiate benign and malignant nodules
• Most solitary thyroid nodules are cold
• Most cancers arise in cold nodules
• Risk of cancer in a cold nodule is 10-15%
• Risk of tumour in a hot nodule is negligible
• Scintigraphy of minimal use in evaluation of solitary thyroid nodules
• Useful in recurrent thyroid swellings and retrosternal goitres

Ultrasound

• Will define solitary and dominant nodules
• Will distinguish solid and cystic lesions
• Most sonographically solid lesions are benign
• Cancer can occur in the wall of a cystic lesion
• No reliable criteria to distinguish benign and malignant lesions
  

Fine needle aspiration cytology

• Should be first line investigation of the solitary thyroid nodule
• With experienced cytologist diagnostic accuracy can be >95%
• Possible cytopathological diagnoses are:
  Benign
  Malignant
  Indeterminate
  Inadequate
• Can distinguish benign and malignant tumours except follicular neoplasms
• Diagnosis of follicular carcinoma depends on the visualisation capsular
• If follicular neoplasm on FNA lesion will require surgical excision
• False negative rate less than 5% in most institutions
• Definitive FNA cytology allows:
  Non-operative treatment with benign disease
  Appropriate surgical treatment of thyroid cancers at initial operation
  Surgery can be avoided in anaplastic tumours and lymphomas
  Reduces total number of thyroid lobectomies
  Increases yield of thyroid cancers
• Brown fluid - thyroid cyst
• Thick brown fluid - MNG
• Scanty, bloody, cellular material - papillary/follicular
  

Indications for surgery after FNA cytology

• All proven malignant nodules
• All cytologically diagnosed follicular neoplasms
• All lesions exhibiting an atypical but non-diagnostic cellular pattern on cytology
• Cystic nodules which recur after aspiration
• When on clinical grounds the index of suspicion of malignancy is high even if the cytology report suggests it is benign