PRIMARY IGA GLOMERULONEPHRITIS AND SCHONLEIN-HENOCH PURPURA NEPHRITIS - CLINICO-PATHOLOGICAL AND IMMUNOHISTOLOGICAL CHARACTERISTICS

Abstract

A comparative analysis of clinicopathological and immunohistological characteristics was performed of 205 [human] cases with primary Ig[immunoglobulin]A nephritis and 35 with Schoenlein-Henoch purpura nephritis (purpura nephritis). Diagnostic criteria for primary IgA nephritis were set out so that IgA was the most prominent Ig or, at least, equal to IgG and/or IgM, if present, irrespective of mesangial or peripheral localization. In primary IgA nephritis, 1/2 of the cases were discovered by asymptomatic proteinuria, 1/3 presented recurrent upper respiratory tract infection and gross hematuria, 1/4 abdominal pain and in a few cases joint pain, while purpura nephritis was associated with a significantly higher incidence of such systemic symptoms as abdominal and joint pains and purpura. Both diseases shared a tendency toward conspicuous hematuria in contrast to the modest proteinuria, with normal renal function in 3/4-2/3. Of 35 with purpura nephritis, 4 showed preceding proteinuria and were regarded as primary IgA nephritis until purpura appeared. The glomerular pathology had a common feature in that there was frequent occurrence of mesangial proliferative and focal and segmental lesions. The immunohistology in the 2 diseases was indistinguishable with regard to the glomerular Ig and mediators, whether purpura was present or absent. By analogy with SLE [systemic lupus erythematosus], primary IgA nephritis may be regarded as ''sine lupo'', lying on 1 side of the nosological spectrum with less systemic symptoms, whereas purpura nephritis may occupy the other side with more systemic aspects. Epimembranous granular deposition of IgA in both diseases is the most characteristic morphological expression of circulating immune complexes.