Primary mediastinal large B-cell lymphoma. Hematoxylin and eosin staining illustrating the clear cytoplasm of the neoplastic cells and the fibrotic bands without annular distribution that compartmentalize the tumor cells. Tumor cells express CD20 and most express CD30, which is weak and heterogeneous. The arrow depicts a multilobulated Hodgkin Reed Sternberg-like cell. Black bars = 50 μm; gray bar = 20 μm.