Definition
Lymphoma is the name of a diverse group of cancers of the lymphatic system, a connecting network of glands, organs and vessels whose principle cell is the lymphocyte.
What is the lymph system?
The lymph system is an interconnected network of thin tubes and nodes that carries white blood cells. These cells fight infections and are vitally important for our well-being. You can read more about the lymph system in the article - What is the lymph system?. So when a lymphocyte (a type of white blood cell) that is a part of the lymph system becomes cancerous, it may grow and multiply to form a lymphoma.
Description
Cancer cells are the descendants of a single normal cell in which genetic errors, or mutations, have occurred. These errors cause the cancer cells to over- or under-produce proteins that abnormally affect the cell's behavior - causing these cells divide too fast or fail to die when they should.
Cancer cells are typically clonal meaning that the descendent cells share the defects of the parent cell, but they can acquire additional mutations.
The malignant behavior, such as how aggressive or slow growing it might be, is determined by the cell type, the kinds of mutations, and sometimes the host environment.
There are as many kinds of cancers as there are cell types: skin, lung cancer, and blood cell cancers, etc. In cells, genetic errors occur in the basic building blocks of DNA called genes. These errors might occur randomly when the cell divides, or they may result from exposure to environmental toxins called carcinogens - meaning able to cause cancer.