This is membranoproliferative glomerulonephritis (MPGN). Those cases that are idiopathic and 'primary' are divided into types I and II by pathologic findings. As seen here, the glomerulus has increased overall cellularity, mainly increased mesangial cellularity. Some cases of MPGN are 'secondary' to underlying conditions such as autoimmune diseases, infections, and malignancies, among others.

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