Thyroid and Parathyroid

ultrasound examination, and selective venous catheterization (with calcitonin assay),
including hepatic vein and jugular sampling after pentagastrin stimulation. An
increase in the hepatic veins before an increase in the cervical veins indicates hepatic
metastases. Nuclear imaging studies with 131I metaiodobenzylguanidine (MIBG),
dimercaptosuccinic acid (DMSA), and 99mTc-sestamibi all have been used but are
only occasionally helpful. Positron-emission tomography (PET) scanning appears to
be useful in selected patients. Some clinicians examine the liver laparoscopically to
. rule out liver metastases
Ultimately prognosis is related to disease stage. The 10-year survival rate is
approximately 80 percent, and only 45 percent in those patients with lymph node
involvement. Survival also is significantly influenced by disease type. It is best in
patients with familial non-MEN medullary thyroid cancer, followed by those with
MEN IIA, then those with sporadic disease, and it is worst in patients with MEN IIB.
Patients with tumors that stain poorly for calcitonin and with a heterogeneous
antibody uptake do worse than patients in whom calcitonin staining is increased and
. homogeneous
With the identification and localization to chromosome 10 of the gene that causes
MTC, it is now possible to screen family members and identify children at risk of
developing MTC. Performing thyroidectomy at the C-cell- hyperplasia stage or
before, after the age of 5 years, will prevent MTC and improve survival rates. Patients
. with MEN IIA and MEN IIB are at risk for pheochromocytoma
Anaplastic Carcinoma
This tumor is one of the most aggressive malignancies, with few patients surviving 6
months beyond diagnosis. The incidence of anaplastic carcinoma has dropped to
about 1 percent of thyroid carcinomas in the United States. The decrease in incidence
is probably a result of the decrease in iodine-deficient (endemic) goiter, which was a
precursor for this condition. Most anaplastic carcinomas arise from differentiated
thyroid cancers. There is a female-to-male ratio of 1.5:1, and the majority of tumors
present in the seventh and eighth decade of life. Presentation before the age of 50
. years is rare
Pathology
Tumor growth is extremely rapid, with macroscopic invasion of surrounding tissues.
Lymph node involvement frequently is present. Microscopically, sheets of cells are
seen, with marked heterogeneity. Cells may be spindle- shaped, polygonal, or large,
multinucleated cells. Foci of more differentiated cells may be seen, either follicular or
papillary in pattern. Anaplastic tumors originally described as small-cell are
recognized to be lymphomas or less commonly medullary carcinomas of the thyroid
. gland and should be treated as such
Clinical Manifestations
Patients typically are elderly females with a history of a lump in the neck that has
been present for some time before rapidly enlarging and becoming painful. Associated
symptoms such as dysphonia, dysphagia, and dyspnea are common. The tumor is hard
and may be fixed to surrounding structures or may be ulcerated (Fig. 36-28). Lymph
nodes usually are palpable at presentation. Evidence of metastatic spread also may be