Hyperechoic Structure

Hypoxemic Renal Shock

Diabetic Nephropathy

Acute and Chronic Glomerulonephritis Chronic Pyelonephritis

Analgesic Nephropathy

Septic–Toxic Kidneys Severe Metabolic Disorders

Light-chain Deposition Disease, Waldenström Macroglobulinemia Amyloidosis

Infiltration by Lymphoma Atrophic Kidneys

Light-chainDeposition Disease, Waldenström Macroglobulinemia

Light-chain deposition disease is a nonspecific condition that leads to renal failure based on the precipitation of light-chain paraproteins in the distal tubules, a hypercalcemic tubulopathy in hypercalcemia syndrome, and/or an accompanying deposition of amyloid. Similar changes are encountered in Waldenström macroglobulinemia and amyloid kidney.

Ultrasound may demonstrate renal enlargement and increased cortical echogenicity. Often there is only mild enlargement with an indistinct parenchymal texture (Fig. 9.49).

Fig. 9.49 Light-chain deposition disease, hypercalcemic crisis, renal failure.

a Right kidney (N): parenchyma has a somewhat indistinct structure and appears slightly hyperechoic to the liver (L). Prominent medullary pyramids.

b Acute renal failure requiring dialysis in a patient with paraproteinemia (and initial hypercalcemia) and a plasmacytoma. The kidneys are still of normal size (N, cursors). The parenchyma shows markedly increased echogenicity with enlarged, hypoechoic to anechoic medullary pyramids (arrows).

Amyloidosis

Amyloidosis is also associated with an increase in cortical echogenicity and prominent hypoechoic pyramids. We see, then, that these diffuse structural changes occur in a variety of diseases and cannot be considered specific sonographic features; indeed, they are very nonspecific. Only if the underlying disease is known can the echogenicity changes be referred to a specific renal complication. In the beginning the kidneys are normal in size and markedly hyperechoic. In later stages they become smaller and even diminutive at the dialysis stage (Fig. 9.50).

Fig. 9.50 Presumed renal amyloidosis: echogenic renal cortex with increased parenchymal volume causing slight narrowing of the sinus echo complex. Hypoechoic, illdefined medullary pyramids (rheumatoid arthritis, renal failure with nephrotic syndrome). L = liver; N = kidney.

Generally the detection of renal atrophy does not point to a specific cause (Fig. 9.51), although bilateral atrophic kidneys are more likely to have a diabetic etiology (only in the late dialysis stage) or a glomerular cause, or may result from analgesic nephropathy.

Unilateral renal atrophy, or bilateral atrophy that differs in severity between the sides, usually has a different cause such as pyelonephritis or vasopathy (Fig. 9.52).

As the name implies, the kidneys appear small in ultrasound. The parenchyma is thinned, and the renal outlines are smooth (glomerular, diabetic) or wavy (pyelonephritis

Fig. 9.51 Small, hyperechoic right kidney (N, arrows) due to an unknown cause. Slight structural irregularity. L = liver.

Fig. 9.52 Renal atrophy (85 mm) due to arteriosclerosis and arteriolosclerosis: irregular, rarefied, slightly hyperechoic parenchyma (cursors) with a correspondingly broadened sinus echo.