Pneumothorax Caused by Osteochondroma: Clinical Insights, Imaging Features, and Management

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Introduction

Pneumothorax caused by osteochondroma is an extremely rare clinical entity but represents a striking example of how benign bone tumors can lead to life-threatening thoracic complications. Osteochondroma, also known as osteocartilaginous exostosis, is the most common benign bone tumor, typically occurring in adolescents and young adults. While usually asymptomatic, in rare cases it may cause significant complications depending on its size, growth direction, and anatomical location.

When an osteochondroma arises from the ribs and projects intrathoracically, it can penetrate the pleura and injure lung parenchyma, resulting in pneumothorax, hemothorax, or recurrent respiratory infections. This column presents a case of a 16-year-old boy with hemoptysis and pneumothorax due to rib osteochondroma, reviewing the etiology, pathophysiology, epidemiology, clinical presentation, imaging features, treatment, and prognosis.

Case Presentation

A 16-year-old boy presented to the emergency department with a two-week history of persistent cough, occasionally producing small amounts of bright red hemoptysis. He reported a short-haul flight a few days before the onset of symptoms. There was no fever, and his only positive family history was ankylosing spondylitis.

On physical examination, he was hemodynamically stable, with normal coagulation and infection markers. His hemoglobin was measured at 8.4 mmol/L.

Initial Imaging

  • Chest X-ray (Figure 1) revealed a small left-sided pneumothorax associated with basal pleural adhesions and focal consolidation in the left upper lobe.

  • CT angiography (Figures 2–4) excluded pulmonary embolism but demonstrated left pneumothorax with consolidation and pleural adhesions. Crucially, a 4 cm spiculated bony protrusion was identified, originating from the visceral aspect of the left sixth rib. This lesion penetrated the visceral pleura, causing parenchymal laceration, pulmonary contusion, and hematoma.

Further Evaluation

  • 3D reconstruction and chest X-ray (Figure 5) confirmed the pneumothorax and rib abnormality.

  • Gross pathology following surgery confirmed the diagnosis of rib osteochondroma with intrathoracic growth, directly responsible for the pneumothorax.

Cause and Etiology

Osteochondroma is a benign bone tumor that arises from aberrant cartilage growth at the metaphysis, usually during skeletal development. The lesion is characterized by cortical and medullary continuity with the parent bone, capped by cartilage.

  • Etiology:

    • Often sporadic, though associated with EXT1/EXT2 gene mutations in hereditary multiple exostoses (HME).

    • Mechanical trauma and abnormal epiphyseal growth have also been implicated.

    • In rib osteochondromas, intrathoracic projection is rare but possible.

When rib osteochondromas grow inward toward the pleural cavity, the sharp bony protrusion may puncture the visceral pleura, causing air leakage into the pleural space (pneumothorax).

Pathophysiology

The pathophysiology of pneumothorax secondary to osteochondroma is mechanical:

  1. Bony protrusion from rib osteochondroma → projects into the pleural cavity.

  2. Direct penetration of the visceral pleura → creates a defect allowing alveolar air to leak.

  3. Air accumulation in the pleural space → causes lung collapse, dyspnea, and chest pain.

  4. Additional parenchymal injury → results in pulmonary contusion, hematoma, or hemoptysis.

The severity of the pneumothorax depends on the size and location of the osteochondroma, the degree of pleural penetration, and the presence of adhesions.

Epidemiology

  • Osteochondroma prevalence: accounts for 20–50% of benign bone tumors.

  • Typical sites: femur, tibia, humerus; rib involvement is rare (1–2% of cases).

  • Thoracic complications:

    • Hemothorax, pneumothorax, pulmonary artery compression, or pericardial injury.

    • Extremely rare in pediatric and adolescent patients, with fewer than 30 cases reported worldwide.

Clinical Presentation

Patients with rib osteochondroma may remain asymptomatic or present with:

  • Chest pain or discomfort

  • Cough and dyspnea

  • Recurrent pneumothorax

  • Hemoptysis (as in this case)

  • Rarely: cardiac tamponade or hemothorax if vascular structures are injured

In our case, the key clinical clue was the combination of pneumothorax and hemoptysis in a young, otherwise healthy boy with no infection markers.

Imaging Features

Chest X-Ray (Figure 1 & Figure 5)

  • Revealed a small left pneumothorax with basal pleural adhesions.

  • Subtle signs of consolidation in the left upper lobe.

CT Angiography (Figures 2–4)

  • Excluded pulmonary embolism.

  • Identified a sharp, spiculated bony lesion (4 cm) arising from the sixth rib.

  • Demonstrated cortical and medullary continuity with parent bone, confirming osteochondroma.

  • Showed direct penetration into the pleura and lung parenchyma, with air leak, pulmonary contusion, and hematoma.

Treatment

The patient underwent single-port video-assisted thoracoscopic surgery (VATS).

  • The osteochondroma was resected at its base on the rib.

  • Adjacent lung lacerations and pleural defects were repaired.

  • Coagulation of the pleura was performed to prevent recurrence.

Post-operative Outcome

  • Chest X-ray showed complete resolution of pneumothorax.

  • The patient was discharged on post-operative day 2 in good condition.

Prognosis

  • Excellent after resection: recurrence is extremely rare if complete excision is achieved.

  • Risk of recurrence: higher in incomplete resection or in patients with hereditary multiple exostoses.

  • Malignant transformation: <1% in solitary osteochondroma, but up to 5–10% in HME, typically to secondary chondrosarcoma.

For rib osteochondromas, surgical removal is generally curative, especially when complications like pneumothorax have already occurred.

Quiz

1. What is the key chest X-ray finding in this case?

A) Apical left pneumothorax
B) Pleural adhesions
C) Left upper lobe consolidation
D) All of the above

2. What is the most direct mechanism by which osteochondroma causes pneumothorax?

A) Malignant transformation to chondrosarcoma
B) Pleural inflammation leading to rupture
C) Direct penetration of the visceral pleura by a bony protrusion
D) Secondary infection and abscess rupture

3. Which surgical approach was used in this case?

A) Open thoracotomy
B) Needle aspiration only
C) VATS (video-assisted thoracoscopic surgery)
D) Conservative observation

Answer & Explanation

1. Answer: D) All of the above. Explanation: The X-ray showed a small left pneumothorax, basal pleural adhesions, and left upper lobe opacity, all contributing to the final diagnosis.

2. Answer: C) Direct penetration of visceral pleura by bony protrusion. Explanation: The pneumothorax results from sharp bony spicules puncturing the visceral pleura, not from infection or malignant transformation.

3. Answer: C) VATS (video-assisted thoracoscopic surgery). Explanation: Minimally invasive thoracoscopic surgery allowed safe resection of the rib osteochondroma and repair of pleural defects, preventing recurrence.

Figures and Captions

Figure 1. Chest X-ray showing a small left pneumothorax with basal pleural adhesions and left upper lobe opacity.
Figure 2. Axial CT angiography reveals pneumothorax and rib osteochondroma.


Figure 3. Sagittal CT angiography confirming intrathoracic rib protrusion.

Figure 4. Axial CT angiography demonstrating bony continuity and pleural penetration.

Figure 5. Chest radiograph with basal pneumothorax and pleural adhesions.

Conclusion

Pneumothorax caused by osteochondroma is a rare but serious complication of an otherwise benign rib tumor. Accurate diagnosis relies on careful interpretation of chest imaging, particularly CT, which demonstrates the continuity of bone structure and its intrathoracic extension.

Prompt surgical management with VATS ensures resolution, prevents recurrence, and provides an excellent prognosis. Awareness of this entity is crucial for radiologists and thoracic surgeons when evaluating unexplained pneumothorax in young patients.

References

[1] F. Murphey, J. Choi, M. Kransdorf, D. Flemming, and G. Gannon, “Imaging of osteochondroma: variants and complications with radiologic-pathologic correlation,” Radiographics, vol. 20, no. 5, pp. 1407–1434, 2000.

[2] D. Kitsoulis, K. Galani, A. Stefanaki, E. Paraskevas, A. Karatzias, and N. Agnantis, “Osteochondromas: review of the clinical, radiological and pathological features,” In Vivo, vol. 22, pp. 633–646, 2008.

[3] Y. Xu, H. Li, C. Xu, and G. Xu, “Rib osteochondroma causing hemothorax and pneumothorax: case report and literature review,” J Thorac Dis, vol. 6, no. 6, pp. E136–E139, 2014.

[4] S. Kim, J. Kim, Y. Choi, and H. Park, “Intrathoracic rib osteochondroma causing pneumothorax: a case report,” Korean J Thorac Cardiovasc Surg, vol. 47, no. 6, pp. 547–550, 2014.

[5] A. Malik, N. Choudhary, and S. Rao, “Osteochondroma of rib presenting with spontaneous hemothorax: a rare case report,” Interact Cardiovasc Thorac Surg, vol. 15, no. 3, pp. 549–551, 2012.

[6] E. Tsuchiya, K. Yamada, and T. Horiuchi, “Thoracic complications of rib exostoses,” Ann Thorac Surg, vol. 63, pp. 1473–1475, 1997.

[7] J. Kaya, P. Dagdelen, and A. Ozturk, “Management of rib osteochondroma with thoracoscopic resection,” Interact Cardiovasc Thorac Surg, vol. 26, pp. 1074–1076, 2018.

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