Abundant cartilage formation of congenital pulmonary airway malformation--a case report.

Congenital pulmonary airway malformation (CPAM) of the lung is an uncommon developmental anomaly. We report an unusual case of type 1 CPAM with abundant cartilage in a 5-year-old boy. On chest radiography, a left lung mass was detected incidentally, and tumor resection was performed under the impression of a benign tumor. The pathological examination of the mass revealed abundant cartilage in the walls of malformed bronchioles with partially cystic dilatation. We think that this case represents a cartilaginous variant of CPAM. The cartilaginous variant of CPAM should be differentiated pathologically from other pulmonary neoplasms containing abundant cartilage, such as chondroid hamartoma.