Increased cellularity and expression of adhesion molecules in muscle biopsy specimens from patients with rheumatoid arthritis with clinical suspicionof vasculitis, but negative routine histology

Objective-Histological analysis of random quadriceps muscle biopsy specimen s can be used to detect vasculitis in patients with rheumatoid arthritis (R A). This study aimed at determining the immunohistological features in pati ents with clinical suspicion of rheumatoid vasculitis, but without a transm ural infiltrate or fibrinoid necrosis of the vessel wall on routine histolo gy. Methods-Three groups of patients with RA were studied: (a) without clinical signs of vasculitis (n=6); (b) with recent onset of extra-articular featur es and a clinical suspicion of vasculitis but normal routine histology (n=1 1); and (c) with recent onset of extra-articular features and vasculitis, h istologically proved either in muscle or other biopsy specimens (n=14). A c ontrol group of patients with osteoarthritis was also included (n=5). Froze n sections from quadriceps muscle biopsy specimens were analysed with monoc lonal antibodies to detect CD3, CD4, CD8, CD68, ICAM-1, VCAM-1, and HLA-DR. The slides were evaluated using a semiquantitative scoring system (0-4). Results-The mean scores gradually increased from group 1 to 3, leading to s ignificant differences between groups I and 2, but not between groups 2 and 3 for most markers (p < 0.05). Thus the pathological changes were similar for the two groups with clinical signs of vasculitis, even when the convent ional histological evaluation was negative. Higher immunohistological score s were associated with perivascular infiltrates on routine histology. Conclusion-The pathophysiological events leading to vasculitis are reflecte d by the changes in the quadriceps muscle biopsy specimens. The data indica te that the sensitivity of examination of muscle biopsy specimens for the d iagnosis of rheumatoid vasculitis can be increased by the use of new criter ia.