Papillary carcinoma cytology and pathology

Abstract

Papillary carcinoma is the most common thyroid cancer, constituting 75-85% of the malignant thyroid lesions in regions where iodine-deficient goiter is no longer present (1). It represents most of the thyroid cancers that occur in children and young adults, whether idiopathic or related to radiation. A small proportion is familial. Generally, papillary carcinomas grow slowly and spread mostly by lymphatic vessels. The majority are infiltrative, without a capsule. Both gross and microscopic features are varied, depending on cellularity, amount and type of stroma, and the content of colloid (2). Nondiploid papillary cancers (3) and those having N-ras mutations are more likely to have metastases and to cause death (4). Furthermore, cyclo-oxygenase-2 and matrix metalloproteinase-2 expression have been reported to be significantly higher in older patients with more aggressive papillary carcinomas (5,6). Cytologic and pathologic features of the more common variants of papillary carcinoma are described in this chapter and in Chapter 66 with clinical descriptions in Chapter 66. © 2006 Humana Press Inc.