Background@#
Light-chain
amyloidosis (AL) is the most common form of systemic
amyloidosis. This study aimed to evaluate the usefulness of
laboratory tests for
light-chain clonality and
bone marrow (BM) findings in
AL amyloidosis. @*
Methods@#We retrospectively enrolled
patients newly diagnosed with
AL amyloidosis on pathological examination
who underwent a BM
biopsy.
Laboratory test data for
light-chain clonality were collected and compared.
Amyloid deposits were identified with H&E,
Congo red, and PAS
stains. @*Results@#We reviewed 98
patients with
AL amyloidosis.
Light chain clonality (λ, 64 cases; κ, 34 cases) was detected by
serum immunofixation
electrophoresis (IFE) (63.3%),
urine IFE (70.8%),
serum protein electrophoresis (PEP) (44.9%),
urine PEP (44.8%),
serum free
light chain (SFLC) ratio (79.5%), and BM
immunohistochemistry (IHC) (85.7%). Flow cytometric (FCM) assay identified aberrant BM
plasma cells in 92.9% of cases. BM
amyloid deposits were identified in 35 of the 98 cases (35.7%); 71.4% (25/35) were
Congo red-positive, and 100.0% (35/35) were PAS-positive. @*Conclusion@#
Laboratory tests for detecting
light-chain clonality in
AL amyloidosis in order of
sensitivity include FCM assay for aberrant
plasma cells, IHC for
light chains on BM
biopsy or clot section, SFLC ratio, and
serum and
urine IFE.
Congo red staining of BM samples remains an important tool for identifying
amyloid deposits in BM.
Periodic acid-Schiff (PAS)
staining can be useful in diagnosing some cases of
Congo red-negative
amyloidosis.