Nodular keloids are those keloid lesions that take a round and raised form, and measure 5 millimeters in diameter or more. Over time, nodular keloid lesions can grow in size and once they measure over 2 centimeters are by definition called tumors. These cut offs, to call a keloid lesion nodule or tumor, are quite arbitrary and do not have any particular significance.
We do not understand as to why some keloid lesions take a flat shape, or nodular. What we do know, is that there are many patients whose keloid always maintains a flat shape. Often, patients may have a mixture of keloid lesions, some nodular, some flat or linear. Below is an example of a nodular keloid lesion in an African American young male with several nodular keloids.