Late-onset congenital cystic adenomatoid malformation of the lung. Embryology, clinical symptomatology, diagnostic procedures, therapeutic approach and clinical follow-up.

BACKGROUND: Congenital cystic adenomatoid malformation of the lung (CCAM) is an embryonic developmental anomaly of an unknown etiology usually diagnosed antenatally by imaging techniques. A minority of cases may not be identified by prenatal imaging techniques and may go unnoticed for the first 6 months of their extrauterine life. Due to its rarity, physicians are unlikely to suspect the condition.

OBJECTIVES: To highlight the embryology, clinical symptomatology, diagnostic procedures, therapeutic approach and clinical follow-up of a series of 12 patients with late-onset CCAM.

METHODS: An observational study which offers the description of the clinical presentation, diagnostic methods, treatment and follow-up of 12 patients with late-onset CCAM.

SETTING: A 600-bed teaching hospital in a reference area of 350,000 inhabitants.

PATIENTS: 12 patients from 1983 to 1999.

RESULTS: Twelve diagnosed cases of late-onset CCAM. Mean age at diagnosis: 6.7 years (range: 6 months to 23 years).

CLINICAL PRESENTATION: 9 out of 12 (75%) with repeated lung infections, 2 out of 12 (16%) chance finding, and 1 case (8%) with pneumothorax. On pathological examination, 7 were found to be CCAM type I and 4 CCAM type II according to Stocker's classification; 1 patient is currently awaiting surgery. The diagnostic method of choice nowadays is a computed tomography (CT) scan performed in the 7 more recent cases; in the former 5 cases an isotopic lung scan was done (and in 2 of them a bronchography was also performed).

TREATMENT: 11 patients were operated: 8 lobectomies, 2 segmentectomies and 1 localized resection. Mean follow-up: 8 years (range: 6 months to 16 years).

COMPLICATIONS: One reintervention due to a reappearance of the lesion in the patient who underwent localized resection of the CCAM. No cases of malignancy were found.

CONCLUSIONS: Late-onset CCAM is an infrequent illness which requires a high level of clinical suspicion. It usually presents in the form of repeated infections. The most frequent pathological forms are type I and II (Stocker). The diagnostic method of choice is the CT scan. The recommended treatment is radical surgery of the lesion once diagnosis has been established. Malignancy and relapses are very infrequent when radical surgery is not postponed.