Bronchioloalveolar carcinoma arising in congenital cystic adenomatoid malformation in a child: a case report and review on malignancies originating in congenital cystic adenomatoid malformation.

A type I congenital cystic adenomatoid malformation (CCAM) in the left lower lobe was removed from a 11-year-old boy with a 3-month history of recurrent pneumonia. As incidental finding, a bronchioloalveolar carcinoma (BAC) was found in the lung parenchyma adjacent to the cyst. A left lower lobectomy was performed. At 18 months after surgery the patient is well and free of neoplastic disease. To the best of our knowledge, this association has not been reported previously in a pediatric patient. Malignancies complicating CCAM are rarely seen, but have been reported in adults. Including our case, eight cases of BAC and five cases of rhabdomyosarcoma (RMS) in association with CCAM have been reported so far. As CCAM can host metaplastic mucous cells, primitive mesenchymal cells and differentiated but poorly organized striated muscle fibers, it has been proposed that CCAM may act as a predisposing condition for oncogenesis. Our experience adds further support that CCAM can act as a premalignant lesion. Previous reports of both BAC and RMS in asymptomatic CCAM suggest prompt resection shortly after diagnosis.