Extralobar Sequestration with Histologic Changes of Congenital Cystic Adenomatoid Malformation in the Adult

Dear Editor:

A 68 year-old male presented with recurrent episodes of non-productive couph, over the last 6 months. Chest CT-scan revealed an atelectatic area of the left lung (Fig. 1 A/B). Subsequent bronchoscopy showed an ‘ectopic' bronchus, arising from the left main bronchus, proximal to the origin of the left upper lobe bronchus. CT-Angiography demonstrated an anomalous pattern of arterial blood supply to the atelectatic lung (Fig 1 C). Exploratory left thoracotomy revealed a mass of pulmonary parenchyma lying outside the normal investment of the visceral pleura, in form of extralobar sequestration (ELS), communicating however with the tracheobronchial tree. The lesion was resected after meticulous identification and ligation of the corresponding vessels and bronchus. Histologic examination confirmed changes of Stocker type II congenital cystic adenomatoid malformation (CCAM), which coexisted with the pulmonary sequestrum (Fig 2 A, B).

Learning points:

- CCAM is a paediatrician entity and is exceptionally rare in adults.

- Stocker type II lesions, (which have a fibromuscular wall and are characterized by cysts lined with cuboid-to-columnar epithelium), occasionally coexist with pulmonary sequestration. In such cases, on the one hand there is communication with the tracheobronchial tree as in CCAM, while on the other, vascular supply and venous drainage are the same as in ELS.

Figure 1: A/B: CT – scan, showing atelectatic left lung area. C: CT-Angiography showing the anomalous pattern of systemic vascular supply from the thoracic aorta.

Figure 2: A: Smooth muscle fibres and cartilage intermingled with adenoid structures, irregular blood vessels and dilated bronchioles. H&E X 20. B: Small hyperplastic adenoid structures surrounded by a dense muscular stroma. H&E X 100