A chest radiograph performed on an asymptomatic 47 year old man under investigation for hypertension was suspicious of a retrocardiac mass. Contrast enhanced computed tomographic (CT) scanning demonstrated a large low attenuation mass encasing the oesophagus. It extended from the carina to the diaphragm and measured 15 × 7 cm in diameter (fig 1). The air space consolidation and small pleural effusion at the base of the left lung were judged incidental findings as they had completely resolved 1 week later when a CT guided biopsy was attempted. A barium swallow showed that the oesophagus was of abnormal calibre but emptied promptly. Video assisted thoracoscopic biopsy was undertaken.

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Figure 1

 CT scan showing a large retrocardiac mass encasing the oesophagus.

Histological examination (fig 2) showed a part cystic and part solid mass with elements of oesophageal smooth muscle and serosal surface. Ectatic vascular spaces with flat inconspicuous endothelial linings gave it a “sponge-like” appearance. Some of the spaces contained lymph and others blood. It was decided that these malformations were benign and best classified as a lymphangioma.

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Figure 2

 Thoracoscopic biopsy specimen showing ectatic vascular spaces, some containing lymph and others blood.

Oesophageal lymphangioma is an exceptionally rare cause of a mediastinal mass in adults. It is a benign proliferation of lymphatic vessels and sacs that can grow in an infiltrative fashion.¹ This is the largest described in the literature.² Complications are usually due to mass effect. Treatment is either surgical resection or conservative. Given his lack of symptoms, this patient elected for the latter.