NCIt definition : A malignant tumor arising from the epithelial cells. Microscopically, the neoplastic
epithelial cells form cylindrical spatial configurations (cribriform or classic type
of adenoid cystic carcinoma), cordlike structures (tubular type of adenoid cystic
carcinoma), or solid structures (basaloid variant of adenoid cystic carcinoma). Adenoid
cystic carcinomas mostly occur in the salivary glands. Other primary sites of involvement
include the lacrimal gland, the larynx, and the lungs. Adenoid cystic carcinomas spread
along nerve sheaths, resulting in severe pain, and they tend to recur. Lymph node
metastases are unusual; hematogenous tumor spread is characteristic.;
Alternative definition : NCI-GLOSS: A rare type of cancer that usually begins in the salivary glands.;