Cartilaginous variant of congenital adenomatoid malformation of the lung

We report the occurrence of an unusual variant of congenital adenomatoid malformation (CAM) of the lung in a 16-year-old male. Abundant cartilage in the walls of malformed bronchioles, an extremely rare finding in CAM, distinguishes this lesion from the usual forms. We present the roentgenographic, computed tomographic, and pathologic features of this lesion as well as its embryologic implications. In addition, two similar cases are reviewed, one of which has been briefly discussed in a previous publication. Cartilaginous CAM should be distinguished from another lesion with abundant cartilage, the so-called pulmonary hamartoma.