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Abstract: TH-PO437

AA Amyloidosis Presenting With Renal Amyloidoma

Session Information

Category: Glomerular Diseases

  • 1301 Glomerular Diseases: Fibrosis and Extracellular Matrix

Authors

  • Gunasekaran, Deepthi, Yale University, New Haven, Connecticut, United States
  • Luciano, Randy L., Yale University, New Haven, Connecticut, United States
Introduction

Amyloidoma is a localized tumor like deposit of amyloid protein. It has been described in a variety of tissues including skin, soft tissue, respiratory tract, and spleen; commonly in the absence of systemic disease. Very few cases of amyloidoma of the kidney are reported. Here, we describe a rare case of systemic amyloidosis with a renal mass showing biopsy proven AA amyloidosis.

Case Description

A 59-year-old male without comorbidities was admitted to the hospital following a motor vehicle collision with lower back pain. Physical exam was significant for 2+ pitting edema in bilateral lower extremities. Labs revealed a creatinine of 7.8 mg/dL from 1.0 mg/dl, four years ago. Urine albumin creatinine ratio was elevated at 4.1 g/g of creatinine. Further work up was significant for elevated CRP, positive Hepatitis C antibody and viral PCR. CT of the abdomen showed a 3.5 cm solid renal mass arising from the anterior aspect of the lower pole of the right kidney and L2-L3 osteomyelitis.
Biopsy of the mass and renal parenchyma showed enlarged glomeruli with marked mesangial expansion by amorphous, pale eosinophilic and silver negative material. Similar deposits were also seen in the interstitium and in perivascular distribution. Congo red stain was positive for amyloid in glomerular (mesangial), perivascular and interstitial areas. Immunohistochemistry for Amyloid A was positive. He was started on maintenance hemodialysis and was discharged on long term intravenous antibiotics for osteomyelitis.

Discussion

The radiographic features of amyloidosis are typically non-specific. In early stages, kidneys may be enlarged but in 50% of cases, they are small with thinned cortex. Our case demonstrates a rare instance of renal amyloidoma formation by a focal, tumor like infiltrative process as seen on CT abdomen. Radiographic findings may precede the clinical presentation and can expedite further work up and treatment. In the work up of solid renal mass, amyloidosis must be considered along with more common conditions such as renal cell carcinoma, multiple myeloma or lymphoma.