Immunoperoxidase and immunofluorescence in lymph node biopsies

A comparison study was made of staining for immunoglobulin by immunofluorescence and immunoperoxidase in 23 lymph node biopsies. Cryostat sections were stained for immunoglobulins using a direct technique while paraffin-embedded sections were stained for immunoglobulins using the peroxidase-antiperoxidase (PAP) technique. Of 23 cases studied, including seven reactive hyperplasias and 16 lymphoid cancers, there was agreement between the two techniques in 18 cases. Nine of 14 non-Hodgkin's lymphomas showed agreement of results. All reactive hyperplasias showed complete agreement and had a distinctive pattern by both immunofluorescence and immunoperoxidase. Fixation, reagent specificity, and sensitivity of the methods may account for some of the discrepancies noted. Immunoperoxidase staining may be a useful diagnostic aid, particularly when immunofluorescent staining is not possible.