Immunoglobulin M Nephropathy in Adults: a Clinicopathological Study

There is no data specifically on the clinical and immunopathologic features of Immunoglobulin M nephropathy (IgMN) in adults with kidney diseases in Pakistan. We retrospectively reviewed our adult native renal biopsy records from May 2001 to April 2010 and identified 57 cases out of a total of 1753 records labeled as IgMN on final histopathological analysis. Among these, 41 cases were included in the present analysis. Their relevant data items were collected from the case files and biopsy reports. The mean age of this cohort was 30.21 ± 10.12 years. The male-female ratio was 1.15:1. The most common presentation was idiopathic nephrotic syndrome. Hematuria and hypertension at presentation were noted in 24 (58.5%) and 10 (24.4%) patients, respectively. The most common morphologic change was glomerular mesangial cell proliferation, found in 28 biopsies (68.3%). Mesangial matrix expansion was noted in 16 (39%). Minor glomerular alterations were noted in 5 cases (12.2%) and focal segmental glomerulosclerosis in 4 (9.8%). Immunofluorescence microscopy showed diffuse mesangial positivity of IgM in all specimens. Subdominant IgA was noted in 6 cases (14.6%). Complements C3 and C1q were found in 28 (68.3%) and 21 (51.2%) patients, respectively. Our results show that IgMN is not very common in adults. Its clinicopathological spectrum is similar to that described from the neighboring countries, showing a spectrum of morphologic changes ranging from minor changes to FSGS.