The complementary role of histology and proteomics for diagnosis and typing of systemic amyloidosis

Abstract

The tissue diagnosis of amyloidosis and confirmation of fibril protein type, which are crucial for clinical management, have traditionally relied on Congo red (CR) staining followed by immunohistochemistry (IHC) using fibril protein specific antibodies. However, amyloid IHC is qualitative, non‐standardised, requires operator expertise, and not infrequently fails to produce definitive results. More recently, laser dissection mass spectrometry (LDMS) has been developed as an alternative method to characterise amyloid in tissue sections. We sought to compare these techniques in a real world setting. During 2017, we performed LDMS on 640 formalin‐fixed biopsies containing amyloid (CR+ve) comprising all 320 cases that could not be typed by IHC (IHC−ve) and 320 randomly selected CR+ve samples that had been typed (IHC+ve). In addition, we studied 60 biopsies from patients in whom there was a strong suspicion of amyloidosis, but in whom histology was non‐diagnostic (CR–ve). Comprehensive clinical assessments were conducted in 532 (76%) of cases. Among the 640 CR+ve samples, 602 (94%) contained ≥2 of 3 amyloid signature proteins (ASPs) on LDMS (ASP+ve) supporting the presence of amyloid. A total of 49 of the 60 CR‐ve samples were ASP–ve; 7 of 11 that were ASP+ve were glomerular. The amyloid fibril protein was identified by LDMS in 255 of 320 (80%) of the IHC–ve samples and in a total of 545 of 640 (85%) cases overall. The LDMS and IHC techniques yielded discordant results in only 7 of 320 (2%) cases. CR histology and LDMS are corroborative for diagnosis of amyloid, but LDMS is superior to IHC for confirming amyloid type.

The Pathology of Amyloidosis in Classification: A Review

“…While immunofluorescence in frozen sections and immunohistochemistry in paraffin sections have traditionally been used for amyloid typing, mass spectrometry has emerged as the method of choice for the typing of amyloid proteins, in particular in paraffin sections [6][7][8][9][10][11][12][62][63][64][65][66][67][68][69][70][71][72].…”

Use of ixazomib, lenalidomide and dexamethasone in patients with relapsed amyloid light‐chain amyloidosis

“…In all cases, a diagnosis of amyloidosis was confirmed by Congo‐red staining of a tissue biopsy with demonstration of characteristic birefringence under cross‐polarised light. The amyloid subtype was confirmed by immunohistochemistry with specific antibodies, or by mass spectrometry (Rezk et al , ). All patients had a detailed baseline assessment including serum free light chains (sFLC), serum protein electrophoresis, imaging and organ assessment including cardiac biomarkers.…”

Cytomegalovirus reactivation after bortezomib treatment for multiple myeloma and light chain amyloidosis

“…A diagnosis of amyloidosis was confirmed by Congo red staining of a tissue biopsy with demonstration of characteristic birefringence under cross‐polarised light. The amyloid subtype was confirmed by immunohistochemistry with specific antibodies, or by mass spectrometry . Hereditary amyloidosis was excluded by gene sequencing as appropriate.…”

“…The amyloid subtype was confirmed by immunohistochemistry with specific antibodies, or by mass spectrometry. 9 Hereditary amyloidosis was excluded by gene sequencing as appropriate. All patients had a detailed baseline assessment of organ function with biomarker assessments and imaging, including SAP scintigraphy, where appropriate.…”