Fifteen cases of pure supradiapragmatic lymphoma with initial prominent antero‐superior mediastinal involvement displaying a B‐cell pattern of reactivity were studied. These cases occurred in six men and nine women with a median age of 33 years at diagnosis (range, 23 to 75 years). Supradiapragmatic peripheral lymphadenopathies were present in three cases, and intrathoracic extension to the lung, pericardium, or pleura was possible. In five cases a thymic origin was obvious. All cases exhibited a B‐cell pattern of differentiation, with a great variety of histopathologic aspects associated with a high frequency of fibrosis and/or necrosis. Hodgkin's disease was initially misdiagnosed in four cases. The evolution was purely local, with extrathoracic extension in five cases, at the ultimate phase of the disease. The prognosis appeared to be poor with only five patients still alive at a median survival time of 16 months. A complete chemoresistance and radio‐resistance was observed in seven cases; only two complete remissions were achieved with aggressive chemotherapy. Prolonged remission could be achieved after surgical reduction of the mass. Primary B‐cell mediastinal lymphoma appears to be a distinct clinical entity with local evolution and resistance to therapy. A new therapeutic regimen, which could include surgery in some cases, should be found for this disease.

The karyotypes of 21 patients with chronic B cell leukemia were studied using lymphoblastoid cell lines obtained with the aid of the Epstein-Barr virus. Ten patients had a normal karyotype and eleven patients, an abnormal. There is no single characteristic anomaly, but certain types were more frequent, i.e., 14q+ as a result of a translocation 11;14, trisomy 12, and an isochromosome 17q. Abnormalities in these same three chromosomes have been found in other hematologic malignancies. It is postulated that loci with control cell proliferation are present on chromosomes 12, 14, and 17.

The CD23 antigen density was evaluated by a cytofluorometric technique in 55 patients with chronic lymphocytic leukemia. The quantification method was based on the use of biological standards in indirect immunofluorescence. The CD23 antigen density was correlated with the percentage of CD23 positive cells, but antigen density appeared to be a more informative parameter. CD23 antigen density was lower in stage B than in stages A or C patients, and higher in patients undergoing chemotherapy or previously treated than in untreated patients. There was a significant negative correlation between CD23 antigen density and serum gamma globulin and IgG levels, that existed only in patients in an advanced stage of the disease. CD23 antigen density was higher in patients with abnormal bone marrow reticulin pattern. Serum gamma globulin level was lower in these patients, as well as in patients with prognostically unfavorable histologic bone marrow infiltration pattern. These data emphasize the interest of antigen density as an additional parameter and the complex relationship between CD23 expression, hypogammaglobulinemia, bone marrow histologic findings, and treatment in chronic lymphocytic leukemia.

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