ATTR- and AFib amyloid - two different types of amyloid in the annular ligament of trigger finger.

INTRODUCTION: Histological examination of tissue specimens obtained during surgical treatment of trigger finger frequently encountered unclassifiable amyloid deposits in the annular ligament. We systematically explored this unknown type by a comprehensive analysis using histology, immunohistochemistry, and quantitative mass spectrometry-based proteomics. METHODS: 205 tissue specimens of annular ligaments were obtained from 172 patients. Each specimen was studied by histology and immunohistochemistry. Tissue specimens obtained from ten patients with histology proven amyloid in annular ligament were analysed by label-free quantitative proteomics. Histological and immunohistochemical findings were correlated with patient demographics. RESULTS: Amyloid was present as band like deposits along the surface of annular ligament, dot like or patchy deposits within the matrix. Immunohistochemistry identified ATTR amyloid in 92 specimens (mostly patchy in the matrix), while the band like deposits of 100 specimens remained unclassifiable. Proteomic profiles identified the unknown amyloid as most likely of fibrinogen origin. The complete cohort was re-examined by immunohistochemistry using a custom-made antibody and confirmed the presence of fibrinogen alpha-chain (FGA) in a hitherto unclassifiable type of amyloid in annular ligament. CONCLUSION: Our study shows that two different types of amyloid affect the annular ligament, ATTR amyloid and AFib amyloid, with distinct demographic patient characteristics and histomorphological deposition patterns.

Rheumatoid necroses in the forefoot.

BACKGROUND: The incidence and morphological features of rheumatoid necroses (RN) in the forefoot are unknown. METHODS: Biopsy material from 223 patients with seropositive rheumatoid arthritis (RA) was examined morphologically. The incidence and morphological features of RN in the forefoot were evaluated. RESULTS: RN was found in 65% of cases, which had not been suspected clinically. It was correlated with pain in 69% of cases. CONCLUSIONS: Rheumatoid necrosis contributes to the development of pain and foot deformation. It can be a significant factor worsening the clinical behavior in seropositive RA patients.