Anterior mediastinal lipoma : Case report

Abstract

The objective of this work is to present a case of mediastinal lipoma, due to the rarity of this location and its clinical presentation, which in other reported cases turned out to be asymptomatic.

A 10-year-old boy with a history of respiratory infections and obstructive bronchitis. It is accompanied by productive cough and respiratory difficulty. On admission, he presented hypoventilation, with crackles and expiratory wheezing. An anterposterior and lateral chest X-ray was performed, which revealed a homogeneous opacity with a defined lateral border, extrapleural, projecting over a large part of the left upper lobe and retrosternal space and suggesting a mass in the anterior mediastinum. Complete blood count, coagulation and tumor markers (β-HCG and α-fetoprotein) were normal. The parasternal ultrasound shows a homogeneous and hyperechoic mass measuring 8 cm in diameter, with well-defined contours. The color Doppler study did not show vascularization. The mass widely contacts the adjacent structures (thymus, heart, trachea and esophagus) without infiltrating them. There was a slight tracheal displacement to the right side. There is no evidence of adenopathy, pleural or pericardial effusion. Pathology: Macroscopically, the lipoma is an encapsulated, lobulated, soft, yellowish mass. Microscopically, it is composed of mature adipocytes, separated by thin fibrous septa with a network of capillaries.

The most important differential diagnosis, myxoid liposarcoma, may have a similar clinical-radiological behavior and resemble histology. However, liposarcoma is very rare in this age group and, in addition, the lipoma does not usually present nuclear atypia or pleomorphism. Myxoid liposarcoma typically presents the chromosomal abnormality t(12;16) (q13;p11). Mediastinal lipomas are rare and represent 1.6 to 2.3% of all tumors in this location. The prognosis is excellent, although there may be recurrences in case of incomplete resection. There have been published cases of spontaneous resolution of unresected or partially resected tumors. In our case, a complete excision of the tumor was performed, so there was no recurrence and the patient is asymptomatic 4 years after surgery.