Renal amyloidosis

Renal amyloidosis is rare as an isolated entity but can be associated with systemic amyloidosis.

Epidemiology

Renal involvement is estimated to affect a large proportion of the patients with systemic amyloidosis, with about half of them dying of renal failure complications .

Clinical presentation

It usually manifests as nephrotic syndrome:

• fever
• abdominal pain
• hypertension
• proteinuria
• edema
• urinary symptoms when urinary tract is involved

Pathology

Etiology

• primary amyloidosis
• secondary amyloidosis: aging, chronic infection, chronic inflammatory diseases, tumors, rheumatoid arthritis, Hodgkin disease

Associations

• familial Mediterranean fever 
• Castleman disease 

Complications

• renal failure
• renal vein thrombosis
• obstructive uropathy

Radiographic features

Imaging findings tend to be non-specific and are not always present, but smaller and thinned cortex kidneys are seen in about 50% of patients with systemic amyloidosis . A note is made that, in acute stages, the kidneys may be enlarged. Rarely, amyloid deposition may create focal parenchymal mass lesions .

Ultrasound

• increased echogenicity
• prominent medullary pyramids

CT

• heterogeneous contrast enhancement
• amorphous renal calcifications

MRI

• T2: affected areas are hypointense

Angiography (DSA)

• irregular narrowing and tortuosity of interlobar arteries
• non-visualization of cortical arterial branches