Cortical necrosis commonly manifests clinically as a rapid loss of glomerular filtration rate, often with oliguria, granular casts, and low-level proteinuria. Cortical necrosis may occur at any age. Causes include complications of vascular anastomosis in the transplanted kidney. In the native kidney, it occurs after thrombosis of interlobular or larger arteries, massive cholesterol emboli, septic abortion, or other catastrophic obstetrical complications (including eclampsia), and in the neonate, it occurs as complications of sepsis and placental hemorrhage.

Ischemic acute tubular injury describes a lesion of simplification of the tubules, which commonly manifests clinically as a rapid loss of glomerular filtration rate, often with oliguria, granular casts, and low-level proteinuria. Ischemic acute tubular injury may occur at any age, with varying underlying causality. Isolated acute tubular injury is often recoverable; however, the prognosis is poor if part of multiorgan failure. Episodes of ischemic acute tubular injury are now recognized to increase risk of chronic kidney disease long-term.

Systemic sclerosis (scleroderma) has a strong predilection in women, with onset typically between ages 30-50 years. Scleroderma kidney disease occurs in 60%-70% of patients with systemic scleroderma, mostly in those with a diffuse, rather than limited, form of cutaneous scleroderma. Kidney disease is evident by hypertension, proteinuria, and loss of glomerular filtration rate. Scleroderma kidney crisis develops in about 10%-20%, and presents as new onset malignant hypertension with acute kidney injury.

Proliferative glomerulonephritis with monoclonal immunoglobulin deposits (PGNMID) is a condition where monoclonal immunoglobulins are deposited in the glomerulus. Patients are typically older than 50 years at presentation, but there is a wide age range (20-81 y). Presenting features include nephrotic-range proteinuria in about half, hematuria in three-fourths, and reduced glomerular filtration rate in two-thirds. Only a third have detectable circulating monoclonal protein at presentation, and multiple myeloma is rare, even during follow-up.

Light chain proximal tubulopathy is due to accumulation of monotypic light chains within proximal tubules in patients with a monoclonal immunoglobulin due to low mass or smoldering multiple myeloma (about half of patients), or with monoclonal gammopathy of renal significance. Patients commonly also have other kidney lesions related to abnormal monoclonal immunoglobulin, eg, AL amyloid or light chain deposition disease. The proximal tubulopathy may manifest as Fanconi syndrome with aminoaciduria, phosphaturia, glycosuria in the presence of normal serum glucose, and proximal renal tubular acidosis.

Cryoglobulinemic glomerulonephritis (GN) is caused by intracapillary, capillary wall (often subendothelial), and mesangial cryoglobulin deposits, giving a membranoproliferative pattern of injury. Patients have nephritic/nephrotic syndrome with various levels of kidney function. Purpura and arthralgia occur in about one-third, with vasculitis affecting skin and kidneys less commonly. Abnormal serologic studies include low C4 in three-quarters and low C3 in half. All 3 types of cryoglobulins, including those due to both monoclonal and polyclonal immunoglobulins, can cause cryoglobulinemic GN, although most commonly it occurs in settings of type II (“mixed”) cryoglobulinemia secondary to hepatitis C virus (HCV) infection.

Amyloidosis is a systemic disease caused by amyloid deposition, which may be due to a monoclonal protein, hereditary disorders, or other conditions (see also AL Amyloidosis). The type is diagnosed by immunofluorescence (IF), immunohistochemistry (IHC), and/or mass spectrometry (MS). Hereditary amyloids are autosomal dominant, and are caused by mutation in one of various proteins, most commonly transthyretin (A TTR) but also apolipoprotein AI, AII, or AIV (A Apo-AI/II/IV); gelsolin (A Gel), lysozyme (A Lys), cystatin C (A Cys), and fibrinogen Aα-chain (A Fib).

Amyloidosis is a systemic disease caused by amyloid deposition, which may be due to a monoclonal protein, hereditary disorders, or other conditions (see also Hereditary and Other Non-AL Amyloidoses). The type is diagnosed by immunofluorescence (IF), immunohistochemistry, or mass spectrometry. Patients with AL amyloid are middle-aged or older adults. Kidney involvement by AL amyloid typically manifests by nephrotic syndrome. Patients may also show signs related to the underlying plasma cell dyscrasia, such as anemia, and other organ involvement, which may manifest as neuropathy, heart failure with arrhythmias, hepatosplenomegaly, and more rarely macroglossia.