Rounded Atelectasis

Also called folded lung or Blesovsky syndrome. A peripheral area of lung that collapses and folds into itself against thickened visceral pleura, forming a round or oval pleural-based mass that looks like a tumour but is benign.

• Typically 2 to 7 cm across, in the posterior or lower lobes, and often bilateral.
• Mechanism: a pleural effusion causes compressive atelectasis, the visceral pleura then fibroses and contracts, and the adjacent lung folds in and becomes trapped, with vessels and bronchi dragged toward the mass.
• Commonest cause is asbestos related pleural disease (benign asbestos effusion); other causes are tuberculosis, empyema, heart failure, post-surgical or post-radiation pleural disease, rheumatoid disease, and uraemic pleuritis.
• Frequency: found in about 10 to 20% of patients with asbestos related pleural disease on CT.

Usually asymptomatic and found on imaging; some have cough, pleuritic chest pain or breathlessness from the underlying pleural disease.

• Signs are those of pleural thickening (reduced expansion, dullness) or are absent.
• History of asbestos exposure, past effusion, tuberculosis or empyema.
• Differential diagnosis: primary lung cancer, metastasis, mesothelioma, pulmonary infarct, round pneumonia, pulmonary sequestration, organising pneumonia, lung abscess, fibrous tumour of the pleura.
• Complications: usually none; mild restriction; diagnostic confusion leading to unnecessary surgery; coexisting malignancy that must not be missed.

Chest X-ray: peripheral mass, 2 to 7 cm, abutting thickened pleura, often with volume loss.

• CT chest (the key test) shows all of these: a round or wedge-shaped, pleural-based mass; the comet tail sign (bronchovascular bundles curving into the mass, like the tail of a comet); thickened adjacent pleura; volume loss in the affected lobe; sharp margin on the lung side; and avid, homogeneous enhancement after contrast.
• Air bronchograms within the mass are common.
• PET-CT may show mild to moderate uptake and does not exclude benign disease.
• CT-guided needle biopsy when features are atypical (no comet tail, no pleural thickening, mass not abutting pleura, spiculated edge, growth, or cavitation).
• Follow-up CT over 1 to 2 years documents stability, and rapid growth should lead to biopsy.

Typical lesions need no treatment: reassure the patient and explain that the mass is collapsed lung, not cancer.

• Surveillance CT at 3 months, 12 months and 24 months; after 2 years of stability, no further imaging unless symptoms appear.
• Biopsy or thoracoscopic wedge resection for any atypical feature, a growing or cavitating lesion, or a high-risk patient (smoker with a history of cancer).
• Treat the underlying pleural disease:
  • Tuberculosis: isoniazid 5 mg/kg (maximum 300 mg), rifampicin 10 mg/kg (maximum 600 mg), pyrazinamide 25 mg/kg (maximum 2 g) and ethambutol 15 mg/kg daily for 2 months, then isoniazid and rifampicin daily for 4 months, with pyridoxine 10 to 25 mg daily.
  • Heart failure effusion: furosemide 40 to 80 mg daily with fluid restriction.
  • Empyema: antibiotics and chest drainage with intrapleural alteplase 10 mg plus dornase alfa 5 mg twice daily for 3 days when loculated.
• Decortication is reserved for symptomatic patients with a trapped lung and significant restriction (forced vital capacity of 60% predicted or less); it improves lung function in most but is rarely needed.
• Symptoms: paracetamol 1 g four times daily for pain; pulmonary rehabilitation for breathlessness.
• Special groups: children (very rare, usually after infection, observe); pregnancy (CT with shielding only if essential; use ultrasound and chest X-ray first); elderly (conservative); asbestos-exposed workers (record exposure, offer smoking cessation with varenicline 0.5 mg once daily for 3 days, 0.5 mg twice daily for 4 days, then 1 mg twice daily for 12 weeks).
• Red flags: enlarging mass, loss of the comet tail, new nodularity, weight loss, haemoptysis, severe pain, hypoxia.
• Follow-up: CT at 3, 12 and 24 months, then none if stable; annual review of lung function if restrictive; lifelong awareness of asbestos related lung cancer and mesothelioma risk.