Anatomic Pathology: Vascular Pathology

48) A small-caliber artery from a kidney needle biopsy sample demonstrates dense waxy homogeneous deposits in the vessel wall compromising the vascular lumen and without any associated inflammation. A Congo red stain was negative. Immunofluorescence staining depicted monoclonal staining only for kappa light chains in the vessel wall. Electron microscopy examination showed finely granular or powdery electron dense deposits in the vessel wall. The BEST diagnosis is:

• Monoclonal immunoglobulin deposition disease (light chain deposition disease) is defined as the deposition of complete or partial monoclonal immunoglobulin components along basement membranes, primarily affecting renal tubules, glomerular capillaries, and arteries.

• By light microscopy, a nodular expansion of glomerular mesangial regions, similar to Kimmelstiel-Wilson nodules, is most characteristic, seen in 60% of cases. Often, glomeruli are diffusely and globally affected, and the mesangial nodules are of similar sizes.

• Tubular basement membranes are typically thickened, in particular along nonatrophic tubules. In addition, arterioles and small arteries can show wall hypertrophy and dense waxy deposits.

• The disease process can spare glomeruli and can be limited to the tubulointerstitial and vascular compartment, reported in 10% to 24% of cases in most series.

• The vascular monoclonal immunoglobulin accumulations occasionally can be massive, leading to individual smooth muscle cell necrosis and mimicking vascular amyloid deposits by standard light microscopic examination. By definition, Congo red staining for amyloid is negative.

• The immunofluorescence microscopy findings are so characteristic in most cases as to be virtually diagnostic. In vessels, there is basal lamina staining around individual myocytes, producing a “spider web” pattern of positivity in the media. Most cases demonstrate monoclonal kappa light chains (κ:λ ratio 9:1).

• The detection of monoclonal light chains in the serum or urine increases the probability that a patient has monoclonal immunoglobulin deposition disease, but it does not accurately predict disease.

Lin J, Markowitz GS, Valeri AM, et al: Renal monoclonal immunoglobulin deposition disease: the disease spectrum. J Am Soc Nephrol 2001;12(7):1482-1492.

Markowitz GS: Dysproteinemia and the kidney. Adv Anat Pathol 2004;11(1):49-63.

Strom EH, Fogazzi GB, Banfi G, et al: Light chain deposition disease of the kidney—morphological aspects in 24 patients. Virchow Arch 1994;425(3):271-280.

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