muramidase and Rheumatoid-Nodule

The expression of PG-M1, the most specific histiocytic marker, has not yet been studied in granuloma annulare (GA) and other palisaded granulomas of the skin. We evaluated the reactivity of PG-M1 with a series of GA and rheumatoid nodules (RN) to establish the sensitivity and potential usefulness of this marker in the diagnosis and characterization of these entities.. Histological sections from 30 GA and 15 RN were immunostained with PG-M1. For comparison, additional sections were stained with KP-1 and lysozyme. The stains were recorded as negative, weakly positive (1+) and strongly positive (2+).. PG-M1 stained all cases of GA (100%). KP-1 and lysozyme stained 26 (86%) and 18 (60%) GA cases, respectively. PG-M1 exhibited a significantly stronger staining intensity (1.8 +/- 0.07) when compared with KP-1 (1.4 +/- 0.13) (p = 0.018) and with lysozyme (0.9 +/- 0.15) (p < 0.0001). All RN were stained by PG-M1 (100%). KP-1 and lysozyme stained 14 (93%) and six (40%) RN cases, respectively. PG-M1 staining intensity (1.6 +/- 0.13) was slightly higher than that of KP-1 (1.4 +/- 0.18) (p = 0.27) and significantly higher than that of lysozyme (0.4 +/- 0.13) (p < 0.0001).. PG-M1 is consistently and strongly expressed by the histiocytic population of GA and RN, being more sensitive and reliable than other histiocytic markers. We recommend its use in difficult cases in which the histiocytic nature of the lesion needs to be confirmed.

Topics: Antibodies, Monoclonal; Antigens, CD; Antigens, Differentiation, Myelomonocytic; Biomarkers, Tumor; Granuloma Annulare; Histiocytes; Humans; Immunoenzyme Techniques; Muramidase; Retrospective Studies; Rheumatoid Nodule; Sensitivity and Specificity; Skin Diseases

Eighteen nodules from patients with rheumatoid disease were studied histologically and immunohistochemically. A continuum of microscopic changes was observed with varying degrees of fibrinoid necrosis, mononuclear cell infiltration and healing by fibrous scarring. In two cases there was focal evidence of arteritis. Fibrin was plentiful in the necrotic areas of nodules. Small amounts of immunoglobulin were identified in plasma cells and as irregular extracellular deposits in and around areas of necrosis. In a single small vein abnormal IgG was detected. Mononuclear cells surrounding areas of necrosis stained strongly with antisera to ferritin and a cytoplasmic macrophage antigen, stained variably with muramidase (lysozyme) and negatively with alpha-1 antitrypsin antibodies. Perls' stain for ferric iron was almost entirely negative and ultrastructural x-ray microanalysis indicated that the cytoplasm of these cells were entirely free of iron. These findings confirm the chronic inflammatory nature of rheumatoid nodules but provide no support for the view that they originate in areas of vasculitis. A relative lack of cytoplasmic antiprotease along with a strong expression of ferritin appears to be a characteristic feature of macrophages in rheumatoid tissue.

Topics: Adult; Aged; Blood Proteins; Electron Probe Microanalysis; Female; Ferritins; Fibrin; Histocytochemistry; Humans; Immunochemistry; Immunoglobulins; Iron; Male; Microscopy, Electron; Middle Aged; Monocytes; Muramidase; Rheumatoid Nodule

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.

Topics: Granuloma; Histocytochemistry; Humans; Immunoenzyme Techniques; Muramidase; Necrobiosis Lipoidica; Rheumatoid Nodule; Skin; Skin Diseases