Bilateral renal enlargement

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Bilateral enlarged kidneys without focal masses.

• Diabetic nephropathy: Most common cause of bilateral enlarged kidneys, accounting for 50% of cases. May precede chemical evidence of diabetes by a year or so. The echogenicity of the kidneys is normal.
• Acute glomerulonephritis: Enlargement is thought to be due to edema. Patients present with renal insufficiency.
• Vasculitis/Autoimmune: Systemic lupus erythematosus, Wegener (sinusitis and hemoptysis), Goodpasture (pulmonary hemorrhage may be present), Henoch-Shonlein (diffuse purpura), polyarteritis nodosa (multiple aneurysms may be seen on angiography).
• HIV nephropathy: Enlarged, echogenic kidneys with decreased corticomedullary definition, decreased renal sinus fat, parenchymal heterogeneity, and globular renal configuration. About 10% will have medullary hyperattenuation. Striated nephrograms may also be seen.
• Leukemia/Lymphoma: Diffuse infiltration of the kidney with preservation of renal architecture and contour and decreased echogenicity seen early. Later, there is an expansile heterogeneous renal mass with loss of normal renal architecture.
• Autosomal recessive polycystic kidney disease: Massively enlarged hyperechoic kidneys with loss of corticomedullary differentiation.
• Acute interstitial nephritis: Enlarged echogenic kidneys. Initially reported in association with scarlet fever, acute interstitial nephritis is also known as hypersensitivity nephritis and can be due to humoral and cell-mediated responses to infection or medication.

Mnemonic (courtesy of Dr. J.D. Oldan): HAD LAVA (in the kidneys)

References

• Di Fiori JL, Rodrigue D, Kaptein EM, Ralls PW. Diagnostic sonography of HIV-associated nephropathy: new observations and clinical correlation. AJR Am J Roentgenol. 1998 Sep;171(3):713-6.
• Zagoria RJ and Tung GA (1997). Chapter 4. in Genitourinary Radiology: The Requisites. pp 139-140.