Benign vs. Malignant Tumors Cells that multiply excessively but remain at their original site in the body form benign tumors , which usually cause few problems and can be completely removed by local surgery. Benign tumors may arise in any tissue, grow locally and cause damage by local pressure or obstruction. The common feature is that they do not spread to distant sites. Examples of benign tumors of the skin are warts and papillomas. Their cells are abnormal in many ways besides their lack of self-control over cell division.
Malignant tumors have a specific capacity to invade and destroy the underlying mesenchyme.
The general trend in tumor progression is for it to go from bad to worse. There are five major steps involved in metastasis. Invasion and infiltration of surrounding normal host tissue with penetration of small lymphatic or vascular channels. Release of neoplastic cells into the circulation. Survival in the circulation.