Clinical relevance of the histopathological subclassification of diffuse "histiocytic" lymphoma

Because diffuse "histiocytic" lymphoma, which is an immunologically heterogeneous disease, responds well to chemotherapy in some but not all patients, we attempted to identify the morphologic features that might correlate with its behavior and prognosis. We identified five histopathological categories in 66 patients: one with an excellent prognosis (large, cleaved cell, six of eight patients surviving for two years); two with an intermediate prognosis (large, noncleaved and mixed follicular-center cell, nine of 18 and eight of 17, respectively, surviving for two years); and two with a poor prognosis (blastic and pleomorphic pyroninophilic, one of 10 and two of 13, respectively, surviving for two years). The differences among categories were significant (P less than 0.02) and not dependent on stage (P greater than 0.20). Tumors of follicular-center origin had a better prognosis than tumors of nonfollicular-center origin (P less than 0.01). Differences in survival were due to differences in complete response rate. Morphologic subclassification of diffuse "histiocytic" lymphoma may be useful in predicting response to chemotherapy and survival.