Transcript 3. What work ups are needed, if any?

3. What work ups are needed, if any?
• Laboratory Studies
• Thyroid function
– Perform a complete assessment of thyroid
function in any patient with thyroid lumps.
– Higher-than-normal levels of thyroxine ,
triiodothyronine and thyroid-stimulating
hormone (TSH) may indicate thyroid cancer.
– Evaluate serum levels of thyroglobulin, calcium,
and calcitonin.
• TSH suppression test
– Cancer is autonomous and does not require TSH for
growth, whereas benign lesions do require TSH. When
exogenous thyroid hormone feeds back to the
pituitary to decrease the production of TSH, thyroid
nodules that continue to enlarge are likely to be
malignant. However, 15-20% of malignant nodules are
suppressible.
– Preoperatively, the test is useful for patients with
nontoxic solitary benign nodules and for women with
repeated nondiagnostic test results.
– Postoperatively, the test is useful for monitoring
papillary thyroid cancer cases.
Imaging Studies
• Chest radiography, CT scanning, and MRI
– These tests are not usually used in the initial workup of a thyroid nodule,
except in patients with clear metastatic disease at presentation.
– These tests are second-level diagnostic tools and are useful in preoperative
patient assessment.
• Echography
– This imaging study must be performed first in any patient with possible
thyroid malignancy.
– Echography is noninvasive and inexpensive, and it represents the most
sensitive procedure for identifying thyroid lesions and for determining the
diameters of a nodule (2-3 mm).
– Echography is also useful for localizing lesions when a nodule is difficult to
palpate or is deeply seated. Echography images can help determine if a lesion
is solid or cystic and can help detect the presence of calcifications.
– The accuracy rate of echography in categorizing nodules as solid, cystic, or
mixed is near 90%. It may be used to help direct a fine-needle aspiration
biopsy (FNAB).
• Scintigraphy
– Before FNAB, thyroid scintigraphy performed with technetium Tc 99m
pertechnetate (99mTc) or radioactive iodine (iodine I 131 or iodine I 123) was
the initial diagnostic procedure of choice for a thyroid evaluation.
– The procedure is not as sensitive or specific as FNAB for distinguishing benign
nodules from malignant nodules.
– Scintigraphic images of the thyroid are acquired 20-40 minutes after
intravenous administration of the radionuclide.
– In more than 90% of cases, clearly benign nodules appear as hot nodules
because they are hyperfunctioning and have a high captation rate of
radionuclide and, physiologically, of iodine. Malignant nodules usually appear
as cold nodules because they are not functioning.
– Findings from thyroid scanning are helpful and specific in evaluating the
preoperative and immediate postoperative periods for localization of cancer
or residual thyroid tissue and in observing for tumor recurrence or metastasis.
Thyroid scanning can also be useful for diagnosing benign lesions (by FNAB) or
solid lesions (by echography).
FNAB
• FNAB is considered the best first-line diagnostic
procedure for a thyroid nodule; FNAB is a safe and
minimally invasive procedure.
– The accuracy of FNAB results is better than any other test
for uninodular lesions. The sensitivity of the procedure is
near 80%, the specificity is near 100%, and errors can be
diminished using ultrasonographic guidance.
– False-negative and false-positive results occur less than 6%
of the time.
– A thyroid biopsy can also be performed using the classic
Tru-Cut or Vim-Silverman needles, but the FNAB technique
is preferable. Patients comply best with FNAB.
Histologic Findings
• Papillary thyroid carcinoma usually appears as a grossly
firm mass that is irregular and not encapsulated.
• Microscopically, it is multifocal, and a net invasion of the
lymphatics may be demonstrated. Complete or partial
papillary architecture with some follicles is present.
• The thyrocytes are large and show an abnormal nucleus
and cytoplasm with several mitoses. In some cases, the
thyrocytes may have the so-called "orphan Annie eyes,"
that is, large round cells with a dense nucleus and clear
cytoplasm.
• Another typical feature of this cancer is the presence of the
psammoma bodies, probably the remnants of dead
papillae.
Staging
• The staging of well-differentiated thyroid cancers is related to age
for the first and second stages, but it is not related to age for the
third and fourth stages. In the staging protocol, T is tumor, N is
node, and M is metastasis.
• Younger than 45 years
– Stage I - Any T, any N, M0 (cancer in thyroid only)
– Stage II - Any T, any N, M1 (cancer spread to distant organs)
• Older than 45 years
– Stage I - T1, N0, M0 (cancer only in thyroid, may be found in one or
both lobes)
– Stage II - T2, N0, M0 and T3, N0, M0 (cancer only in thyroid and >1.5
cm)
– Stage III - T4, N0, M0 and any T, N1, M0 (cancer spread outside thyroid
but not outside of neck)
– Stage IV - Any T, any N, M1 (cancer spread to other parts of body)