16. Benign tumors of the pleura and lungs

Benign tumours of the pleura and lungs

Benign pulmonary and pleural tumours are uncommon and are often discovered incidentally on chest imaging.
Pulmonary hamartoma is the commonest benign lung tumour; it contains disorganised mature tissues such as cartilage, fat and connective tissue.
Other lesions include inflammatory myofibroblastic tumour, lipoma, leiomyoma, schwannoma and benign vascular lesions.
Pleural tumours include solitary fibrous tumour, lipoma and other rare mesenchymal lesions. A pleural mass must be distinguished from metastatic disease and malignant mesothelioma.

Hamartomas are usually peripheral, well-circumscribed and slow-growing; characteristic intralesional fat and popcorn calcification may be seen on CT.
Endobronchial benign tumours can cause obstruction, distal atelectasis, recurrent pneumonia or bronchiectasis despite benign histology.
Solitary fibrous tumours arise from pleural mesenchymal cells and may be pedunculated or sessile. Most behave indolently, but malignant behaviour or recurrence can occur.

Most patients are asymptomatic. Symptoms depend on size and location and include cough, wheeze, haemoptysis, chest discomfort, dyspnoea or recurrent infection.
Examination is often normal; focal wheeze or signs of collapse/consolidation may occur with endobronchial obstruction.
Ask about growth on previous imaging, smoking, previous malignancy, occupational exposures and systemic symptoms such as fever or weight loss.

Chest radiograph may show a solitary pulmonary nodule or pleural-based opacity. Compare with previous images to establish growth.
Thin-section CT characterises margins, fat, calcification, enhancement, airway relation and pleural attachment. PET-CT may be used when malignancy remains a concern, but uptake is not perfectly specific.
Bronchoscopy is useful for central/endobronchial lesions and permits biopsy. CT-guided biopsy may be considered for peripheral lesions when safe and likely to change management.
Differentials include primary lung cancer, metastasis, granuloma, hamartoma, carcinoid, rounded atelectasis and pleural malignancy. Imaging alone is not always sufficient.

Observation with interval CT may be appropriate for a small lesion with classic benign features and documented stability, following specialist review.
Resection is considered for growth, symptoms, airway obstruction, diagnostic uncertainty or suspicious imaging. Parenchyma-sparing wedge resection or segmentectomy is preferred when feasible.
Endobronchial lesions may be treated bronchoscopically in selected cases; surgery may be needed for irreversible distal lung damage or uncertain pathology.
Complications include recurrent infection, haemoptysis, local compression and recurrence after incomplete excision. Histology and follow-up should guide surveillance.