Richter's syndrome of T-cell lineage (T rex lymphoma).

By definition, Richter's syndrome represents the transformation of low-grade B-cell lymphoma into high-grade B-cell lymphoma, usually refractory to treatment. Exceptional cases of transformation into very aggressive mature T-cell lymphomas have been described as an unusual manifestation of the syndrome in patients died after few months from the diagnosis, despite chemotherapy. The time is ripe to regroup these T lymphomas under a new pathological subset, through the unequivocal alternate naming of 'T rex lymphoma', by analogy with the aggressive behavior of the famous dinosaur (T. rex). In practice, it represents the transformation of low-grade B-cell lymphoma into high-grade T-cell lymphoma, burdened by a very poor prognosis, because of the underlying B-cell lymphoma, which negatively interferes with the immune response of the patient. Against this distinct lymphomatous T clone, the major therapeutic efforts should be addressed.