Benign tumors known as choristomas are typically composed of normal tissue that develops and grows in an abnormal location. A choristoma might consist of some of the cells found in the surrounding tissue but mostly contains other cell types. In the majority of cases, the growth does not contain cells related to the immediate area. The abnormal growths generally remain small in size and may be found anywhere in the body. The tumors may or may not produce symptoms, depending on specific location, and treatment may involve surgery when the tissue interferes with function or causes unpleasant symptoms.
A choristoma usually contains bone, cartilage, and fatty tissue. The bony tissue may contain a substance similar to marrow that generally resembles gelatinous fat, and the cartilage cells generally contain fibrous tissue containing vascular structures. The largest lesions usually measure 3.75 inches (1.5 centimeters) in diameter and often develop into firm nodules. The dermal growths tend to appear beneath the skin of the face, in the oral cavity, and and in the eye.
Choristomas comprise 3% of all conjunctival and corneal tumors in children. The tumor may occur secondary to a familial trait. Masses might also develop on lacrimal glands. These eye tumors may appear as flat, small lesions, or may grow into larger, bulbous, filled masses. Treatment for a choristoma in this region generally requires surgical removal.
Young adults, particularly females, may develop a choristoma on the tongue. Some denture wearers experience choristoma growth on the bony ridges of the gum, and some physicians believe the condition occurs from the irritation or trauma caused by friction between the gum and the denture. If multiple growths occur, the individual sometimes has a condition known as Albright's hereditary osteodystrophy.
When they develop in the gastrointestinal tract, choristomas rarely invade or compress other tissue, but may become obstructive. In the esophagus especially, bleeding and scarring often accompany the growths. Constant irritation commonly causes ulcer formation. Treatment for cutaneous conditions in the gastric region generally include medications classified as histamine receptor (H2) blockers or proton pump inhibitors.
Another type of tumor commonly found in children, a hamartoma, is a benign growth that develops on the head or neck. Unlike a choristoma, a hamartoma contains the same cellular structures as surrounding tissues, but the cells proliferate into an unorganized mass. When choristomas or hamartomas develop in brain tissue, they often produce seizure disorders. Heterotopia, another type of benign growth, typically forms in fetal brain matter and emerges as neuronal tissue that did not extend to the correct part of the brain.