Similar to ALK+ALCL, activation of the JAK-STAT signaling pathway seems to play an important role and is in many cases secondary to STAT3, JAK1, and JAK3 mutations, but also through rearrangements involving ROS1, TYK2 of FRK. Two recurrent chromosomal translocations with characteristic clinicopathological features are recognized. This evidence concerns the gene ALK and anaplastic large cell lymphoma.