ALK-positive large B-cell lymphoma patient-derived xenografts. (A-E) ALK-positive large B-cell lymphoma morphology shows sheets of large neoplastic lymphoid cells with plasmablastic morphology (A), including moderate to abundant cytoplasm and round to irregular nuclei with prominent nucleoli. The neoplastic cells are positive ALK1 (B) and IgA (C), and negative for CD20 (D) and CD30 (E). (F-J) A PDX model of the ALK-positive large B-cell tumor was generated by implanting a tumor fragment underneath the kidney capsule, which generated a tumor mass after 6 to 8 weeks. The morphology of the PDX model (F) was identical to that of the patient's tumor, with strong ALK1 expression (G) and negative for CD20 (H). (I) PDX tumor replacing the implanted left kidney of mouse (right) and uninvolved right kidney on left (millimeters). (J) PDX bivalved showing tan, soft-cut surface of tumor (centimeters).