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 Echography 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)