Biopsies from palisading granulomas of granuloma annulare, necrobiosis lipoidica, and rheumatoid nodules were examined for the presence of lysozyme (muramidase). This enzyme was identified in paraffin-embedded tissues using a primary antibody to lysozyme and the peroxidase-antiperoxidase technic. Some inflammatory cells in the infiltrate of granuloma annulare stained abundantly for lysozyme, whereas those of necrobiosis lipoidica and rheumatoid nodule stained minimally and negatively, respectively. This pattern of staining may be of diagnostic value and suggests that the histiocytoid cells constituting the infiltrate of granuloma annulare are in some way different from the similar-appearing cells of necrobiosis lipoidica and rheumatoid nodule.
Bibliographical noteFunding Information:
From the Department of Dermatology (Padilla, Dahl, Burgdort), and the Department of Laboratory Medicine and Pathology (Mukai, Rosai), University of Minnesota Medical School. Supported in part by National Institutes of Health Research Training Grant TO 1-AM05560. Accepted for publicationS ept. 29, 1982. Reprint requests to: Dr. R. Steven Padilla, University of New Mexico, Departmento f Medicine, Divisiono f Dermatology, 2701 Frontier Place rE, Room 268, Surge Bldg., Albuquerque, NM 87131. *Now an assistant professor of medicinei n the Divisiono f Dermatol-ogy, Department of Medicine, Universityo f New Mexico School of Medicine, Albuquerque,N M.