OBJECTIVES: I. Evaluate the safety of multiple (2-3) administrations of technetium Tc 99m LL2 monoclonal antibody (LymphoScan) in patients with B-cell non-Hodgkin's lymphoma after chemotherapy and/or radiotherapy. II. Describe human antimouse antibody production in these patients. III. Demonstrate that addition of a single LymphoScan study to conventional diagnostic modalities (CDMs) can differentiate between tumor and residual scarring. IV. Determine the diagnostic operating characteristics of LymphoScan to detect residual tumor in patients with radiologically detectable masses. V. Compare patient management plans based on CDMs alone and both CDMs and LymphoScan.