The malignant blasts have the morphology and immunohistochemical features of ALCL cells.

(A) Wright stain of peripheral blood smear. Sections created from cell blocks of the leukopheresis product stain positive with monoclonal antibodies directed against (B) MPO, (C) CD30, (D) EMA, (E) ALK, and (F) granzyme B. Note that ALK staining is present only in the cytoplasm of the malignant cells (E).