This 22-years old presented with cough. A chest radiograph showed a mediastinal mass. The CT scan shows the mass well with some areas of necrosis. The differential is aggressive thymic tumor, lymphoma and germ cell tumor. There is no reason to suspect tuberculosis. In any case, a biopsy is a must.

The biopsy is simple and straightforward using a para-sternal approach. The areas of necrosis have to be avoided. This was done using an 18G coaxial biopsy gun.

The diagnosis was a large B-cell lymphoma.