INTRODUCTION: Congenital cystic adenomatoid malformation (CCAM) is a congenital lung lesion rarely diagnosed in adulthood. We describe a patient with CCAM found to have mixed features of two congenital lung lesions.
CASE PRESENTATION: A 23 year-old female was hospitalized with fever, right upper quadrant pain, and cough. CT scan revealed multiple cystic lesions with air fluid levels in the right lower lobe (image 1). She denied any prior history of pulmonary illness, and her medical history was unremarkable. Blood and sputum cultures were negative. CT scan 3 years prior showed pre-existing cystic lung disease in right lower lobe (image 2).She underwent right-sided thoracotomy. Operative findings included dense consolidation of right lower lobe with multiple abscess cavities. A large arterial feeding vessel was discovered originating from the aorta. Right lower lobectomy was performed and the patient was given a preliminary diagnosis of pulmonary sequestration (BPS). Pathologic examination revealed alveoli with absent cartilage, and cystic structures lined with pseudostratified, ciliated columnar respiratory epithelium (image 3). These histologic features are consistent with congenital cystic adenomatoid malformation (CCAM), a rare congenital lung lesion. This lesion is most frequently diagnosed antenatally, and is very rarely found in adults. The finding of a systemic arterial blood supply represents an exceedingly rare mixed lesion consisting of CCAM and BPS.
DISCUSSIONS: CCAM is rare, occurring in 1 in 25,000–30,000 pregnancies. It results from an insult to the developing bronchopulmonary foregut during the first 6–7 weeks of gestation, resulting in abnormal bronchioalveolar airspaces and absence of alveolar cartilage. Stocker et al. classified this lesion into three histologic types: Type I consists of multiple large cysts (up to 10cm) or a single large cyst. This is the most common (50–70%). Type II contains multiple small cystic structures less than 2 cm. Type III is a bulky, solid mass with cysts less than 0.5 cm. (1) Up to 90% of CCAM lesions are diagnosed antenatally by ultrasound or x-ray, and most are successfully treated by surgical resection in infancy. Very rarely, CCAM can remain undiagnosed into adulthood. Morelli et al. reviewed 45 cases of postnatal and adult CCAM. The most common clinical findings included asymptomatic presentation, recurrent pneumonia, cough, or pneumothorax. Surgical resection is the treatment of choice due to the wide range of etiologies for cystic lung disease in the adult. Histologic confirmation is imperative to exclude malignancy or other causes. (1) Cass et al. report 6 cases of fetal CCAM-BPS lesions diagnosed prenatally, and have described this as a “hybrid” lesion. There are 19 cases of CCAM-BPS lesions in the pediatric literature, all were diagnosed prenatally. All were surgically resected by two years of age, with a survival rate of 94%. (2) At present, there are no adult case reports of a lung lesion with histologic features CCAM and systemic arterial blood supply.
CONCLUSION: Congenital lesions must be considered in an adult with focal cystic lung disease. Surgical resection is essential for definitive diagnosis, and prognosis is excellent. This is a unique case of CCAM with a systemic arterial vessel. This very rare lesion has been described in fetal and pediatric cases but to our knowledge none have been reported in an adult.
DISCLOSURE: Carrie Samiec, No Financial Disclosure Information; No Product/Research Disclosure Information