A benign tumor is an abnormal mass of tissue that lacks the capacity to spread to other locations. The inability to spread is a distinguishing characteristic that separates benign tumors from cancerous tumors. Benign tumors can arise from virtually any body tissue. They are named according to the cell type from which they arise.
Adipocytes
Lipomas are benign tumors composed of fat cells, or adipocytes. The root word "lipo" is the medical term for fat. Lipomas can arise in many different body locations but most commonly occur under the skin, reports the Penn State College of Medicine's Milton S. Hershey Medical Center. Lipomas of the skin, also known as superficial subcutaneous lipomas, frequently arise on the back of the neck, torso and forearms.
Superficial subcutaneous lipomas grow slowly and rarely cause symptoms. Lipomas range in size from less than one-quarter inch up to 4 inches or more, notes the Cleveland Clinic. Women are more commonly affected than are men. Most lipomas occur singly. Some genetic conditions are associated with the growth of multiple lipomas, however.
Melanocytes
Moles are small, benign skin tumors composed of melanocytes. Melanocytes produce the pigment melanin, which gives moles their characteristic tan to brown coloration. Moles are the most common type of benign tumor. The National Cancer Institute reports that most people have 10 to 40 moles. These benign growths usually begin as flat brownish spots, which grow slowly over time, gradually rising above the skin surface. Moles, also known as nevi, are painless.
A mole with unusual physical characteristics is called an atypical mole, or a dysplastic nevus. This type of mole uncommonly transforms into a malignant melanoma, a potentially life-threatening form of skin cancer. Use of sunscreen to protect the skin from the damaging effects of ultraviolet radiation from the sun reduces the risk for the development of malignant melanoma.
Fibroblasts
Fibromas are benign tumors composed of fibroblasts, cells that produce and secrete tough fibrous proteins that hold tissues together. The tumors are characteristically firm, similar to the consistency of scar tissue. Fibromas can arise virtually anywhere in the body, including the mouth, bones, tendons, penis and ovaries. Non-ossifying fibromas of the bone are one of the most common tumors in children and adolescents, reports Children's Hospital Boston.
Fibromatosis is a disorder characterized by multiple fibromas that typically recur after removal. Several variants of fibromatosis can occur in children and adults, reports the New Zealand Dermatological Society on the patient information website DermNet NZ. Although the fibromas associated with fibromatosis are noncancerous, they may grow quickly and cause damage by encroaching on nearby body structures. Deep fibromas generally grow more quickly than superficial tumors. Surgical removal of a fibroma may be necessary if the tumor causes disfigurement, threatens other structures or impairs function.
