A phakoma, or phacoma, is a type of tumor. It is a hamartoma found in phacomatosis.

A hamartoma is a benign malformation resembling a tumor and resulting from faulty development in an organ. It is an overgrowth of mature cells normally found in the affected part. It is composed of an abnormal mixture of tissue elements that develop and grow at the same rate as normal elements but are not likely to compress adjacent tissue. The error here is often in the quantity, the structure, and/or the level of maturation of the tissue components.