Morphologic types of diffuse large-cell lymphoma.

One hundred eighty-seven patients with confirmed diffuse non-Hodgkin's lymphoma were selected from a consecutive series of 391 patients who were evaluated and treated at Stanford University Medical Center. Lymphomas with any degree of nodularity and diffuse lymphomas of "well-differentiated" and "poorly differentiated" lymphocytic type were excluded from this study. Each of four observers identified cases of diffuse large-cell lymphoma from the 187 cases and further subdivided these cases into six morphologic types in accordance with criteria proposed by Strauchen et al. Initial intraobserver and interobserver agreement was relatively low but was greatly enhanced when the initial six morphologic types were grouped as either follicular center-cell or nonfollicular center-cell types. When individual observer results were pooled, statistically significant differences were seen between survival of patients in these two groups, with the patients in the nonfollicular differences were seen between survival of patients in these two groups, with the patients in the nonfollicular center-cell group having a worse prognosis (P = 0.04). This effect of morphologic type appeared to be independent of pathologic stage. Mitotic counts did not correlate with survival.