Malignant lymphoma, diffuse mixed small and large cell. A clinicopathologic study of 47 cases.

The clinical and pathologic features of 47 cases of malignant lymphoma, diffuse mixed small and large cell (diffuse mixed lymphoma) are described. Diffuse mixed lymphomas contained approximately equal numbers of small and large cells (30-70%) and comprised 6% of all non-Hodgkin's lymphomas. They occurred in middle-aged and elderly patients (median age = 63 years), showed a female predominance, and were clinically advanced at presentation. The majority of patients exhibited prominent extranodal disease, which frequently involved multiple unrelated sites and usually occurred in conjunction with nodal disease. A notable morphologic spectrum of lymphoma was seen within this series, including 20 cases of mixed small cleaved and large cell (with cleaved and noncleaved nuclei), eight cases of mixed small lymphocytic and large cell (transformed prolymphocytes and blast-like cells), and 12 cases of mixed small cell and large cell, "immunoblastic" lymphoma (with plasmacytoid, clear cell or hyperconvoluted features). There was no significant difference in response to treatment and survival between those cases with less than 50% large cells and those with greater than 50% large cells. The poorest treatment response appeared to be in patients with mixed small cell and large cell, "immunoblastic" lymphomas. Patients with diffuse mixed lymphoma appeared to show a favorable response to cyclphosphamide, Adriamycin, vincristine, and prednisone (CHOP) and an unfavorable response to other treatment modalities.