Rare Tumors and Benign Diseases

Nonmalignant pathologically benign diseases do not always act clinically benign and may cause dysfunction and exhibit significant symptoms. Initial usage of ionizing radiation for benign diseases dates back centuries with traditional benign diseases amenable to radiotherapy classification as degenerative, inflammatory, hyperproliferative, and functional; however, acute and late effects of radiotherapy have changed the treatment concepts and indications. Life-threatening endocrine orbitopathies, cosmetically disfiguring and functionally disturbing keloids, facial juvenile or adolescent angiofibromas, locally expanding benign central nervous system tumors with pressure effect on normal structures, or pain and serious symptom-causing benign pathologies with lasting quality-of-life effects may justify the low-dose use of ionizing radiation for analgesic and anti-inflammatory end points in case no therapeutic options are available, have failed, or may cause more side effects. Basic concepts that are crucial to understanding benign tumors are reviewed in depth in this chapter.