Background: Intrathoracic lipomas are rare, often asymptomatic and, in this case, discovered by chance on X-ray.
Case report: A 3 year-old girl was admitted because chest X-rays prescribed for a persistent cough showed a mass in the right axillary area. The CT scan showed a mass with density of -80 Hounsfield units, characteristic of adipose tissue. There was a slight rib change in contact with the mass, but radionuclide bone scan showed no area of increased uptake. A chest X-ray performed 3 years earlier had shown such a mass, but it was not recognized at that time. Surgery demonstrated that the mass was extrapleural in location and adhering to the rib which was partly excised. Histologic examination showed the presence of mature adipocytes, but no malignant cells.
Conclusion: The fatty component of an intrathoracic tumor is easily recognized with CT scan. Erosion of bone in contact with it has been reported.