Fig. 3

Morphologic examination and immunohistochemical stains performed on the fine needle aspirate of the mediastinal lymph node. The Diff-Quik™ stained slides show large monocytoid cells with ample blue-grey cytoplasm, round to irregular nuclear contours and immature chromatin (× 500, top-left). The H&E stained sections prepared from the cell block shows a diffuse infiltrate of monocytoid cells with ample cytoplasm and round to irregular nuclear contours (× 200 and × 400, top-right). The tumor cells were negative for CD138 and positive for myeloperoxidase (MPO), CD163 and lysozyme (× 200)