[1516] Heavy Chain-Amyloidosis (AH-Amylodosis): Largest Series of a Poorly Recognized Entity

GA Herrera, DB Thomas. Nephrocor, Tempe, AR; Nephrocor, Uniondale, NY

Background: Less than 10 cases of AH-amyloidosis have been documented in the literature. These have been single case reports with succinct clinical and pathological information. Definition of AH-amylodosis has been restricted to amyloid cases that stain for heavy chains and are negative for kappa and lambda light chains. Whether cases with predominant heavy chain staining but also with monoclonal light chain staining should be included or not in the AH-amyloidosis category or a new category of combined light and heavy chain amyloidosis should be created remains undecided.
Design: Five additional cases of AH-amyloidosis are reported from the files of two institutions during a period of two and a half years in which 1500 renal biopsies were examined, representing the largest series of this entity. A previously reported case by one of the authors is also included for completeness. Clinical and pathological information was collected.
Results: The patients were between 59 and 83 years of age and all of them but one were males. Presentation was proteinuria with or without associated nephrotic syndrome and renal insufficiency. Underlying plasma cell dyscrasias were not recognized prior to the diagnosis of this entity in the renal biopsy. The amyloid material showed light, tinctorial, and ultrastructural characteristics identical to those seen in other types of amylodosis. Four cases were γ and the other two μ-heavy chain related. Two of the cases in addition to predominance of a heavy chain, also had a concurrent monoclonal light chain with equal or less intensity.
Conclusions: AH-amyloidosis is probably more common that recognized. Diagnosis requires careful evaluation of the immunoglobulin fluorescence stains. Clinical presentation did not differ from cases of AL(light chain-related) amyloidosis. None of the patients had a monoclonal gammopathy diagnosed prior to the renal biopsy. All patients are males. Although the definition of AH-amyloidosis up to now has required negative stains for kappa and lambda light chains, it could be broadened to include all cases of amyloidosis with predominant heavy chain staining, or a new categoy of light/heavy chain (ALH) amyloidosis should be created; the latter is more appropriate at this time and we propose to create this new category. The significance of the concurrent monoclonal light chain detection in the amyloid deposits in 2 of the cases is not clear at this time. The pathogenesis of renal AH-amyloidosis in unclear, but is probably similar to that of AL-amyloidosis.
Category: Kidney (does not include tumors)

Wednesday, March 24, 2010 1:00 PM

Poster Session VI # 245, Wednesday Afternoon

 

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