Classificação de glomerulonefrites : proposta para uma nova abordagem baseada em estudo de 700 biopsias renais em microscopia comum, imunofluorescente e eletronica

AUTOR(ES)
DATA DE PUBLICAÇÃO

1997

RESUMO

Past eighty years since Volhard and Fahr put some order in the existent chaos, classification of glomerulonephritis is still a challenge for pathologists and nephrologists. Even the last proposal for classification by the World Health Organization (WHO) is not entirely satisfactory. Three factors contribute for making classification of glomerulonephritis diflicult: 1. A particular glomerular lesion may correspond to several diseases; 2. A single disease may present several glomerular lesions, for example, systemic lupus erythematosus may present different glomerular lesions in the evolution of the disease; 3. Some primary glomerular diseases are named according to the anatomical lesion they present. The present work has the aim to show a new approach to the classification of glomerulonephritis. The proposal is to dissociate the anatomic diagnosis (AD) from the nosologic diagnosis (ND). Both AD and ND should be included in the pathology reporto The anatomic diagnosis is based on light microscopy and the nosologic diagnosis after combining the light, imunofluorescent and electronic microscopy with the clinical and laboratory findings. The most fTequent anatomic "lesion was mesangial proliferative glomerulonephritis (1681700,24%) and corresponded to a large number of diseases, such as Berger s disease, Alport s syndrome, postinfectious glomerulonephritis, thin membrane disease, lupus nephritis, Henoch-Schõnlein purpura and many others. The second most fTequent anatomic lesion corresponded to combined lesions (16.8%) followed by focal segmental glomerulosclerosis (11.4%). In the 700 cases studied, males corresponded to 54.9% of the cases and whites to 84.3%. At the time of the biopsy the mean age of the patients was 28.23 1: 16.4 years. The most fTequent nosologic diagnosis was the complex ML/MPGN/FS corresponding to idiopathic minimallesion disease (ML), idiopathic mesangial proliferative GN with deposition ofIgM (MPGN) and idiopathic focal sclerosis (EF). It corresponded to 21 % of the total of 700 cases followed by lupus nephritis (11 %), idiopathic membranous glomerulonephritis (8%), Berger s disease (7.3%), postinfectious GN (6.1%) and type 1 idiopathic membranoproliferative GN (5.6%). There is much controversy in the literature concerning the complex ML/MPGN/FS. For some authors, this complex is possibly a single disease which has at one side the most benign pole represented by idiopathic minimallesion disease and at the other extreme the idiopathic focal sclerosis which has a more aggressive course. The idiopathic mesangial proliferative GN with deposition of IgM may represent an intermediate phase between these two entities. bur study favors this interpretation. In a total of 16 patients with serial biopsies we found that 12.5% ofthe patients had minimallesion in the first biopsy and focal sclerosis in the second; 31.2% had mesangial proliferative GN in the first and focal sclerosis in the second; and, 6.3% had minimallesion in the first and mesangial proliferative GN in the second. These findings suggest that possibly the complex ML/MPGN/FS represent evolution phases of a single disease. Immunotluorescent and electron microscopy high1y contribute for the determination ofthe nosologic diagnosis. Intense staining for c1q is particuiarly useful ÍR the diagnosis for lupus nephritis. This finding was present in 98.2% of the biopsies of patients with systemic lupus erythematosus. We observed that there is not a single lesion in light, immunotluorescent and electron microscopy that is pathognomic for a. disease except for hematoxylinic bodies thàt were found exclusively in lupus nephritis. We emphasize the need for using light, immunotluorescent and electron microscopy combined with clínical and laboratory findings for establishing the nosologic diagnosis. We believe that this new approach to the classification of glomerulonephritis is simple, easy, didactic and in accord with the biologic phenomenon, that is, it considers the variability of glomeruiar lesions from patient to patient and, in a single patient, the several evolution phases of the disease

ASSUNTO(S)

gromerulonefrites rins - doenças

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