The etiology of thyroid cancer is unknown.
Recent research has suggested that some oncogenes may be involved, including the papillary thyroid carcinoma (PTC) gene.
Associated with radiation to the thyroid gland.
Papillary carcinoma is the most common type of thyroid carcinoma, accounting for approximately 70% of all thyroid tumors.
There is a bimodal appearance to the distribution of this tumor, with a peak from 10 to 30 years of age and a second peak later in life.
Females are more commonly effected, with a ratio from 2:1 to 3:1.
|General Gross Description|
Grossly, the tumor may be 1 to 10 cm in diameter.
On section, the tumor is a white to tan, homogeneous, firm nodule replacing part of the normal thyroid parenchyma.
Some areas of calcification and cystic degeneration may be seen.
While the tumor may seem to have a capsule, invasion of the capsule is almost always the rule.
|General Microscopic Description|
Histologically the tumor is composed of acini in which the lining epithelium is thrown into invaginating folds, with a fibrovascular core.
These invaginations with the fibrovascular core are called papillae (hence the name, papillary carcinoma).
In some instances the papillations may be so extensive as to give the acinus a solid appearance.
The cells lining the papillary are even cuboidal cells, which may seem cytologically benign.
There are characteristic feature of these cells including "Orphan Anne eyes" (nuclei that seem uniformly light blue staining and thus appear empty), characteristic lines that run across the nuclei referred to as "nuclear groves", and psammoma bodies.
The last are spherical, laminated calcifications that lie at the centers of the tips of the papillae.
Indolent, slow growing tumor, with spread to the local lymph node by the time of detection.
Tumors < 2 cm in diameter have an excellent prognosis.
Spread to local lymph node does not significantly worsen the prognosis.
Cotran RS, Kumar V, Robbins SL: Robbins Pathologic Basis of Disease. 5th ed. Philadelphia, W.B. Saunders, 1994, pp. 1137
Harrison's Principles of Internal Medicine, 13th Ed: Isselbach et. al. (eds). New York, McGraw-Hill, 1994, pp.1949
|Synopsis by: T.V.Rajan, M.D., Ph.D. (T96000M80503)|
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