Epithelial inclusions in the lymph nodes. Diagnostic, histogenetic, and prognostic problems.

The capacity of epithelial cancer to invade the lymph nodes is a common notion. Adenopathy may, on rare occasions, be the first clinical sign of an unrecognized cancer. Exceptionally following the discovery in a lymph node of malignant-looking epithelial inclusions, a complete examination of the patient will reveal no primary tumor and the case will remain unexplained. Conversely, it may also happen that upon microscopic examination of the nodes which, for one reason or another, have been removed, benign-looking epithelial inclusions are discovered. In women, these are most often endometrial type glands; in men, they are usually thyroid follicles. The diagnostic, histogenetic, and prognostic problems raised by these various inclusions are, of course, different; however, their one point in common--the ectopic presence of epithelial tissue in a lymph node--and the controversy concerning the benign or malignant nature of certain inclusions, incite this comprehensive study.