A comparative study of Burkitt's and non-Burkitt's "undifferentiated" malignant lymphoma: immunologic, cytochemical, ultrastructural, cytologic, histopathologic, clinical and cell culture features.

Nine patients with "undifferentiated" lymphoma (DUL) of Burkitt's (AMB, four cases) and non-Burkitt's (NB, five cases) types were studied. All specimens stained for a single immunoglobulin light chain indicating a monoclonal B-cell lymphoid proliferation. Striking methyl green pyronine and punctate Oil-Red O staining were demonstrated in both groups. Histologic and cytologic examination demonstrated a lymphoid proliferation with a high mitotic count, a "starry-sky" pattern, prominent cytoplasmic basophilia and vacuolation in both subtypes. The AMB cases showed a predominance of regular nuclei with 3-5 basophilic nucleoli, while the NB cases showed slightly greater nuclear variability with a greater proportion of nuclei containing 1-2 eosinophilic nucleoli. The AMB patients were all children (median, 12 age years) and those with NB were adults (median, age 54 years). The site of presentation in both groups was predominantly extranodal and abdominal. This report emphasizes the considerable immunologic, morphologic, cytochemical and clinical overlap present among the subtypes of "undifferentiated" lymphoma.