Intrathoracic chest wall lipoma: mimicking a soft tissue neoplasm on a chest radiograph.

A 44-year-old eastern European woman presented to the tuberculosis (TB) service after she had a pre-employment TB screening chest radiograph. The frontal anteroposterior (AP) chest radiograph demonstrated a soft-tissue opacity projected over the lateral aspect of the right hemithorax, with poorly defined lateral margins (Fig 1a). The ancillary lateral chest radiograph demonstrated a welldefined soft-tissue lesion projecting posterior to the right breast, across the anterior thoracic wall into the right lung field (Fig 1b). The features were consistent with a soft-tissue extrapulmonary chest wall abnormality. The patient went on to have a computed tomography (CT) scan of the chest, which demonstrated a wellcircumscribed, uniformly homogeneous, low-attenuation lesion measuring 3 cm, which projected across the pleural margin into the right lung field (Fig 1c). It had a mean Hounsfield unit (HU) value of −105 HU and was radiologically consistent with a benign intrathoracic lipoma. There was no mediastinal or hilar lymphadenopathy and the abdominal viscera were normal. Lipomas are benign neoplastic mesenchymal tumours arising from adipose tissue. They are well defined and encapsulated. Intrathoracic lipomas are extremely rare, and usually located centrally in the anterior mediastinum, although they can also be found peripherally. They account for 1.6–2.3% of all mediastinal tumours, 0.1% of all lung tumours and 13% of all benign lung tumours.1 Most are Intrathoracic chest wall lipoma: mimicking a soft tissue neoplasm on a chest radiograph