The interrelationship of Hodgkin's disease and non-Hodgkin's lymphomas--lessons learned from composite and sequential malignancies.

While Hodgkin's disease (HD) and non-Hodgkin's lymphoma (NHL) have long been regarded as distinct disease entities, recent observations suggest a closer association. The analysis of cases in which these diagnoses are made in the same anatomic site (composite lymphomas) or in separate sites (simultaneous or sequential HD and NHL) indicates that this phenomenon occurs more frequently than would be expected by chance alone. The most common form of composite lymphoma is coexistent nodular lymphocyte-predominant Hodgkin's disease (NLPHD) and large cell lymphoma (LCL) of B cell phenotype. This finding is consistent with a B cell origin for the abnormal cells in NLPHD, suggesting that LCL represents a form of histologic progression, with the existence of a clonal relationship between the two components. The association of other forms of HD (nodular sclerosis or mixed-cellularity) and NHL is less common, but still significant. As with NLPHD and LCL, one may observe composite lymphomas, or the diagnosis of HD may precede or follow the diagnosis of NHL. The vast majority of NHLs associated with HD are of B cell origin, most commonly follicular lymphomas. An association between HD and B cell chronic lymphocytic leukemia (CLL) is also observed. In selected cases, Reed-Sternberg (RS) cells are seen in a background of otherwise typical CLL, and some of these patients have progressed to disseminated HD. These findings suggest that, at least in some cases, HD may be clonally related to an underlying B cell malignancy, and that the RS cell may be an altered B lymphocyte.(ABSTRACT TRUNCATED AT 250 WORDS)