Thyroid and Parathyroid

thyroidectomy is about 1 percent. Differentiation of the residual thyroid cancer to
. anaplastic carcinoma occurs in about 1 percent of patients and is almost always fatal
Total thyroidectomy, by removing all residual normal thyroid tissue, facilitates the
uptake of radioactive 131I extrinsic to the gland and helps identify and ablate
metastatic thyroid cancer. Once all thyroid tissue has been removed, thyroglobulin
levels should remain below 3 ng/mL; by monitoring thyroglobulin levels, disease
progress can be followed. When thyroglobulin levels increase, recurrent disease must
. be present and appropriate screening with 131I should be done
The patient with a thyroid nodule that is suspected to be papillary thyroid cancer
should have FNAC performed. When papillary thyroid cancer is diagnosed, the
definitive operation can be done without confirming the diagnosis on histologic
examination. Patients with a nodule that might be papillary cancer should be treated
by thyroid lobectomy, isthmectomy, and removal of any pyramidal lobe or adjacent
lymph nodes. When intraoperative frozen-section examination of a lymph node or of
the primary tumor confirms carcinoma, completion total or near-total thyroidectomy
should be performed. If a definitive diagnosis cannot be made, the operation is
terminated. When final histology confirms carcinoma, completion total thyroidectomy
usually should be performed. For patients who have minimal papillary thyroid cancers
confined to the thyroid gland without angioinvasion, no further operative treatment is
recommended. Treatment with thyroid hormone to suppress TSH is recommended.
Patients at low risk should have serum TSH levels between 0.1 and 1.0 mU/mL,
whereas patients at high risk should have serum TSH levels suppressed to less than
. 0.1 mU/mL
Local recurrence is a serious complication, with a disease-related mortality rate of 33
to 50 percent. Patients with nodal recurrence usually do better than those with tumor
recurrence in the thyroid bed or with distant metastases. Lymph node metastases in
the lateral neck in patients with papillary carcinoma usually should be managed with
modified radical neck dissection, and en-bloc dissection of all fibrofatty tissue and
lymphatic tissue. The jugular lymph node chain is removed, while preserving the
sternocleidomastoid muscle, the internal jugular vein, and the spinal accessory nerve
(which are all taken in a radical dissection). Dissection of the posterior triangle and
suprahyoid dissection usually are not necessary but should be performed when
appropriate. Prophylactic neck node dissection is not necessary in patients with
papillary thyroid cancer, because micrometastases appear to be ablated with
radioiodine therapy. Survival rates for the different treatment modalities are
. summarized in Fig. 36-26
Follicular Carcinoma
Follicular carcinoma, which accounts for about 10 percent of thyroid malignancies, is
decreasing in incidence in the United States. This cancer occurs more often in women,
with a female-to-male ratio of 3:1, and it presents in an older age group, mean age at
presentation of 50 years, compared to a mean age of 35 in patients with papillary
carcinoma. Follicular carcinoma occurs more frequently in iodine-deficient areas, and
. a rare form of familial disease is reported in patients with dyshormonogenesis
Pathology