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- radiology (diagnostics)
- paediatrics (drugs and medicines)
- respiratory system
- pneumonia (infectious disease)
A 10-year-old boy presented with minimal haemoptysis after 1 week of cough and fever. He had a similar presentation 3 years earlier; the diagnosis at that stage was right lower lobe pneumonia. He is HIV uninfected and has no known tuberculosis exposure. Investigations revealed a raised white cell count of 19.0×109/L, raised C reactive protein 217 mg/L, normal clotting studies and the GeneXpert MTB/RIF was negative.
Chest radiograph (figure 1) demonstrated a dense opacity in the right lower lobe posterior segment but without any air bronchograms and sharply demarcated anterior/medial margins, not corresponding to an anatomic boundary. A comparative chest radiograph from 3 years previously (figure 1B) revealed a pre-existing density with an associated air-filled cystic component (the latter not visible on the current radiograph). A CT chest scan was performed to investigate for an underlying lesion and revealed a large subdiaphragmatic vessel arising from the descending aorta, coursing towards a soft tissue density vascularised mass, in the right lower lobe posterior segment, in keeping with a sequestration (figure 2). The presence of multiple associated cystic lesions (with air-fluid levels suggesting super-infection) was radiologically indicative of a hybrid lesion.
Surgery was delayed for 6 weeks while awaiting resolution of the pneumonia. A 4-week course of oral amoxicillin/clavulanate was completed prior to surgery.
A right-sided lateral thoracotomy was performed, confirming a large abnormal arterial vascular supply to the right lower lobe, prompting a right lower lobe lobectomy (video 1). There were adhesions present, probably due to previous lower respiratory tract infection. The lesion was invested within the same visceral pleura as the right lower lobe, consistent with an intralobar sequestration. Histology demonstrated innumerable cysts of varying diameters, lined by respiratory-type epithelium, with walls containing fibrous tissue and scanty smooth muscle fibres, but no cartilage. The cysts merge with relatively normal appearing alveolar tissue. The histological features confirmed that this was indeed a congenital pulmonary airway malformation (CPAM), type 2. With the CT demonstrating a blood supply direct from the systemic circulation, the diagnosis was finalised as a hybrid type 2 CPAM with pulmonary sequestration.
The boy made a complete recovery and the right upper and middle lobe expanded to fill the chest cavity. His duration of hospital stay was 4 days. Follow-up chest radiograph, 2 months later, showed almost complete resolution.
Type 2 CPAM typically manifests with cysts, usually small, ranging from a few millimetres to 2 cm in diameter. Microscopically, cysts have a bronchiolar-like structure and epithelial lining. Cysts can replace the normal lung parenchyma or can be scattered with relatively normal-appearing intervening alveoli. Cartilage is normally absent and mucigenic epithelium is not seen.1 Intralobar sequestration is defined as occurring in a lobe, or part of a lobe, lying within the visceral pleura, isolated from the tracheobronchial tree and associated with an anomalous blood supply.2 3 Hybrid lesions are rare congenital lesions with a combination of a cystic adenomatoid malformation and an anomalous systemic blood supply.2 3
Prenatal diagnosis of hybrid lesions may be difficult. Demonstrating a systemic arterial supply from the aorta to the lesion by colour-flow doppler ultrasound may be diagnostic of a hybrid lesion if both the cystic lesions and the systemic arterial supply are seen.4 Hybrid lesions must be included in the differential diagnosis of recurrent pneumonia, especially if cystic lesions are seen on chest radiograph, and if the patient presents with haemoptysis. The risk for haemoptysis may be significant if there is bleeding from the systemic circulation into the airways, which was the likely scenario in our patient.
Undiagnosed congenital lung lesions must be considered in older children presenting with recurrent pneumonia.
Cystic changes suggestive of congenital pulmonary airway malformation (CPAM) may be visible on follow-up chest radiograph after the acute changes have resolved.
Hybrid CPAM lesions may be more common than previously thought and have risk of haemoptysis; prophylactic surgery is often recommended if this lesion is identified incidentally (either in utero or early childhood), regardless of symptoms, to avoid the fairly predictable complication of pneumonia.
Contributors PG wrote the case presentation and prepared images to be included with the manuscript. SA performed a literature review and wrote the discussion section. JJ and LM assisted with literature review and discussion and also reviewed the paper. PG reviewed the paper and made several modifications to the discussion section.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Patient consent for publication Parental/guardian consent obtained.
Provenance and peer review Not commissioned; externally peer reviewed.