What is the difference between a regular lymph node and a cancerous lymph node?

What it contains: Lymph nodes drain a region of a body of its toxins, pathogens, & dead cells through the lymphatic system. This parallels the venous system. Once the lymphatic fluid from distant cells reaches a node, white blood cells either kill or process the contents. Cancerous nodes simply collected cancerous cells that drained from its territory. The cells then were able to multiply in that node as well.

Nodes are sentinels: Throughout the body, and generate protection, collect/filter lymph harboring micro-oraagnisms and cancer. They contain normal architecture that itself can run amok, or filter cancer cells from other organs. The normal appearance can be distinguished both from lymphoma ad cancer under the scope and with special stains/markers.