ALK-positive ALCLs show a wide morphologic spectrum. (A) Small-cell pattern. A predominant population of small cells with irregular nuclei is associated with scattered large hallmark cells (arrow) showing eccentric lobated nuclei. (B) Giant-cell–rich pattern, showing striking cellular pleomorphism. (C) Common-type ALCL showing several hallmark cells (arrows). (D) Common-type ALCL showing several hallmark cells (arrow) and also a cell with crown-like nuclei (long arrow). (E) Lymphohistiocytic variant showing, in the hematoxylin and eosin-stained section, a single hallmark cell (arrow). Note the eosinophilic paranuclear area. Other cells are nonneoplastic, including histiocytes and plasma cells. Immunostaining of this case for CD30 highlights the scattered malignant cell population.