What is "hamartoma"

n. (context pathology English) A benign mass of disorganized tissue.

n. a focal growth that resembles a neoplasm but results from faulty development in an organ

A hamartoma is a benign, focal malformation that resembles a neoplasm in the tissue of its origin. This is not a malignant tumor, and it grows at the same rate as the surrounding tissues. It is composed of tissue elements normally found at that site, but which are growing in a disorganized mass. They occur in many different parts of the body and are most often asymptomatic and undetected unless seen on an image taken for another reason ( incidentaloma).

Additionally, the definition of hamartoma versus benign neoplasm is often unclear since both lesions can be clonal. Lesions such as hemangiomas, lymphangiomas, rhabdomyomas, adenomas and developmental cysts within the kidneys, lungs or pancreas are interpreted by some experts as hamartomas while others consider them true neoplasms. Moreover, even though hamartomas show a benign histology, it does not eliminate some rare but life-threatening clinical issues such as those found in tuberous sclerosis and neurofibromatosis type I.

Choristomas, forms of heterotopia, are closely related benign tumors, found in abnormal locations. The two can be differentiated as follows: a hamartoma is an excess of normal tissue in a normal situation (e.g. a birthmark on the skin), while a choristoma is an excess of tissue in an abnormal situation (e.g. pancreatic tissue in the duodenum).