A pneumatocele is a cavity in the lung parenchyma filled with air that may result from pulmonary trauma during mechanical ventilation.[1]
Gas-filled, or air-filled lesions in bone are known as pneumocysts.[2] When a pneumocyst is found in a bone it is called an intraosseous pneumocyst, or a vertebral pneumocyst when found in a vertebra.[3]
A pneumatocele results when a lung laceration, a cut or tear in the lung tissue, fills with air.[4] A rupture of a small airway creates the air-filled cavity.[1] Pulmonary lacerations that fill with blood are called pulmonary hematomas.[4] In some cases, both pneumatoceles and hematomas exist in the same injured lung. A pneumatocele can become enlarged, for example when the patient is mechanically ventilated or has acute respiratory distress syndrome, in which case it may not go away for months.[5]
Intraosseous pneumatocysts in the bone are rare and of unclear origin. They are benign and usually without symptoms.[3] They are also found around a sacroiliac joint, and there has been one reported case of an acetabular pneumocyst.[6]
Diagnosis can be made using chest X-ray; the lesion shows up as a small, round area filled with air.[1] Computed tomography can give a more detailed understanding of the lesion.[1] Differential diagnoses – other conditions that could cause similar symptoms as pneumatocele include lung cancer, tuberculosis,[7] and a lung abscess[1] in the setting of hyper IgE syndrome (aka Job's syndrome), as a complication of COVID-19 pneumonitis,[8] or on its own, often caused by Staphylococcus aureus infection during cystic fibrosis.
Treatment typically is supportive and includes monitoring and observation.[1]
Al-Tarawneh. Emad. AL-Qudah. Mohammad. Hadidi. Fadi. Incidental Intraosseous Pneumatocyst with gas-density-fluid level in an adolescent: a case report and review of the literature. Journal of Radiology Case Reports. March 2014. 8. 3. 16–22. 10.3941/jrcr.v8i3.1540. 24967024. 4035364.