The evolving classification systems in lymphoma have been driven by advances in the pathologic characterization of lymphoid malignancies. As evidenced by the detailed pathology descriptions earlier, subdividing heterogenous diseases results in an increasing number of distinct subtypes. This has allowed pathologists to provide more accurate diagnoses and begin to shed light on the molecular mechanisms that underlie these disorders. However, clinical information on these rare subtypes has lagged. Standard staging studies are less useful for these primarily extranodal diseases, although newer technologies such as PET scanning might be useful in detecting and following sites of disease. Optimal management remains undefined. Although these lymphomas are often aggressive, particularly in the case of ETCL, HSTCL, and GD-TCL, standard combination-chemotherapy regimens have only rarely provided durable remissions. Highdose therapy strategies have shown early promise, particularly for HSTCL, although conclusive data to support its routine use is lacking. Other strategies such as biologic therapies as with retinoids for SPTCL have provided durable benefit for some patients with less toxicity. Ultimately, it will take larger series with these rare but increasingly recognized entities to better define a preferred management approach.
