Thoracic lipomas simulating metastasis

Lipomas are common benign soft tissues tumors in adults. Intrathoracic lipomas are uncommon and can develop from the bronchus, lung, mediastinum, diaphragm, and thoracic wall, intrathoracic lipomas arising from the thoracic wall being particularly rare. Thoracic or pleural lipomas originate from submesothelial layers of parietal pleura, can extend into the subpleural, pleural, or extrapleural space, and exhibit slow growth. They can arise from the lateral wall, as well from the mediastinal or diaphragmatic pleura. The low frequency and the very few reports on this entity limit the possibility of defining the correct gender and age predilection. The prevalence has been rising steadily in the past years probably due to the widespread use of chest CT scans. Lipomas usually remain asymptomatic and cause chest pain only rarely. As a result, they tend to be overlooked for a long time and are mostly incidentally diagnosed on chest X-rays or CT scans performed for other reasons. Symptoms, although unusual, might include nonproductive cough, back pain, exertional dyspnea, and a sensation of heaviness in the chest. Lipomas are benign tumors, and surgery is not usually indicated. However, in view of the difficult differentiation between a lipoma and a well-differentiated liposarcoma even after needle biopsy, surgical excision can be a valid option. A more conservative approach can also be considered, with follow-up imaging in order to exclude lesion growth. We present the case of an obese 62-year-old White male (body mass index, 32 kg/m 2) with a smoking history of 68 pack-years. An X-ray of the chest was requested by his general practitioner as part of a routine checkup. The patient had no physical complaints, and his clinical evaluation and laboratory workup were unremarkable. The chest X-ray showed a smoothly marginated round mass in the right lower thorax, peripherally located, with apparent pleural contact or origin. The lesion had homogeneous soft tissue density, without associated calcifications, air bronchogram, bone erosion, or periosteal reaction of the adjacent ribs. A similar but smaller lesion could be seen riding above the right diaphragm (Figure 1). Additionally, the cardiothoracic index was increased. Certain features of lesions on radiographic images can help to narrow the differential diagnosis. The first step should be to locate the lesion precisely, and a lateral chest X-ray is a very useful complement to the posteroanterior incidence. Unfortunately, a lateral chest X-ray was not available in the present case. However, we attempted to determine whether the …