Lipomas are benign tumors of adipose tissue and the most common benign tumor in adults, accounting for 20% of all benign soft-tissue tumors. Lipoma is primarily made up of immature fat cells, although it can also contain mesodermal components other than adipocytes, such as varying quantities of fibrous tissues and blood vessels.5 lipomas within the thoracic cavity are extremely uncommon, which was first described by Fothergil in 1783.6 It can be found in mediastinal, diaphragmatic, bronchial, and pulmonary levels.7
Most people with intrathoracic lipomas are asymptomatic; nevertheless, because lipomas can grow to enormous sizes, they can cause pressure effects, which vary according to the location and size of the lipomas. Symptoms such as dyspnoea and dysphagia might be caused by local compression on neighboring structures such as the trachea or esophagus.7,8 Certain authors have even suggested that the mediastinal structure can be compressed by giant intrathoracic lipoma.9,10 They can also cause various problems like chest pain and fever, as well as invading intercostal spaces and causing rib lysis.11,12 In our case, the patient’s shortness of breath was due to the compressed lung by the massive size of the lipoma, resulting from reduced lung volume.
Although intrathoracic lipoma is usually detected incidentally in a chest X-ray, a homogeneous fat attenuation mass (50 to 150 HU) that creates obtuse angles with the chest wall and displaces neighboring pulmonary parenchyma and arteries on a chest CT permits a conclusive diagnosis.1,2,5,11 Additionally, magnetic resonance imaging (MRI), particularly with fat saturation, is supportive in determining the lipomatous nature of the tumor. Furthermore, MRI helps to distinguish between lipomas and well-differentiated liposarcomas based on margins, signal homogeneity, and septa or nodules.13,14
When possible, total en-bloc excision of lipoma is the definitive treatment choice for preventing future recurrences. Complete surgical excision using the lateral thoracotomy or standard median sternotomy is the most applied surgical approach for intrathoracic lipoma.15 Clamshell thoracotomy has also been employed to remove the bilateral intrathoracic lipoma.16 Whereas, median sternotomy allows complete assessment of both chest cavities and the mediastinum, which ensures en-bloc removal of the encapsulated tumor.17 In our experience, lateral thoracotomy may affect the exposure in case of a large tumor, resulting in rupture of the capsule.2 We believe exposure is the main key to ensure en-bloc resection and choosing surgical exposure. In our previous case we did piecemeal excision of the mass through lateral thoracotomy which caused prolong intrathoracic drain. Though clamshell thoracotomy was mentioned in different articles for bilateral intrathoracic tumor, we avoided it due to our concern of upper limit of the tumor and previous disastrous postoperative experiences related to this particular approach. In the literature, video-assisted thoracoscopic surgery (VATS) has been suggested as a technique for thoracic tumors that are usually pedunculated, tiny in size, and do not have infiltrating growth.5
Intraoperative problems are not infrequent because of severe adhesions with important structures caused by the mass's chronic existence in the thoracic cavity, as in our instance, where it was firmly connected to the innominate vein and superior venacva. Local recurrence of intrathoracic or mediastinal lipomas after resection is infrequent. They may, however, recur locally, and the risk of recurrence following an excision has been documented in the literature to be less than 5%.18 Despite the fact that intrathoracic lipomas are histologically benign, close monitoring and follow-up are required to identify any recurrence.