*In addition to its importance in arriving at a precise diagnosis (eg, is disease restricted to mediastinum?), the clinical setting may affect possible therapeutic options and thus could influence the extent of a clinically applicable workup. Specifically, a workup to determine if very aggressive therapies are appropriate is not required if a patient's performance status or other circumstances would preclude such a therapeutic approach.

†It is very difficult to provide the proportion of cases that would be missed using each of these parameters due to the wide variations reported in the literature and, in some situations, a limited amount of data (see text). The criteria, which at least in some studies would be the least predictive, are morphologic features and Ki-67 proportions and for the less common BCL6 DHL, BCL2 expression. Problems with MYC staining are discussed in the text.