Clinical significance of morphologic subdivision in diffuse large cell lymphoma

Although diffuse large cell lymphomas can be morphologically divided into large cell (DLC) and immunoblastic (IBL) subtypes, the clinical significance of this subdivision remains controversial. The initial diagnostic materials from 85 patients with recorded diagnoses of diffuse large cell lymphoma who were treated at Stanford between 1975 and 1986 with cyclophosphamide, doxorubicin (Adriamycin; Adria Laboratories, Columbus, OH), vincristine, and prednisone (CHOP); methotrexate, bleomycin, doxorubicin, cyclophosphamide, vincristine, and dexamethasone (M-BACOD); or methotrexate, doxorubicin, cyclophosphamide, vincristine, prednisone, and bleomycin (MACOP-B) chemotherapy were retrospectively reviewed by a panel of hematopathologists and classified according to morphologic criteria of the Working Formulation. Based on the criterion of agreement of two of three observers, 60 patients were classified as having DLC, 19 as having IBL, and the lymphomas in 6 patients could not be additionally classified. No significant differences in complete response (CR) rate, freedom from disease progression (FFP), or overall survival were found between the DLC and IBL groups. There was also no significant difference in prognosis between DLC cases additionally subclassified as large cleaved cell (16 patients) and those with large non-cleaved cell (36 patients). Although IBL is considered to be a high-grade lymphoma, the authors concluded that it does not differ significantly in prognosis from DLC lymphoma and, therefore, does not justify a modified treatment selection based on IBL morphologic type alone. Definitive evaluation of the prognostic significance of morphologic subdivision may require a larger cohort of uniformly treated patients.