Representative cases of genetic subtypes of ALCL. (A) ALK-negative ALCL with DUSP22 rearrangement. The tumor cells are positive for CD30 and are negative for ALK, TIA-1, and p63. FISH using a breakapart probe to the DUSP22-IRF4 locus on 6p25.3 shows abnormal separation of the red and green signals on 1 allele (pair of arrows). (B) ALK-negative ALCL with TP63 rearrangement. The tumor cells are positive for CD30, TIA-1, and p63 and are negative for ALK. FISH using a dual-fusion probe to TBL1XR1 on 3q26 and TP63 on 3q28 demonstrates 2 pairs of abnormal fusion signals, indicating 2 copies of inv(3)(q26q28) (TBL1XR1/TP63 fusion; 2 pairs of arrows). (C) ALK-negative ALCL lacking DUSP22 and TP63 rearrangements (triple-negative ALCL). The tumor cells are positive for CD30 and TIA-1 and are negative for ALK and p63. (D) ALK-positive ALCL. The tumor cells are positive for CD30, ALK, and TIA-1 and are negative for p63. Photomicrographs were taken using an Olympus DP71 camera, Olympus BX51 microscope, and Olympus DP Manager image acquisition software at an original magnification of ×400 (insets, ×1000). Original magnification of FISH images, ×600.