Fig. 2

Histological patterns of ALTR. Macrophagic pattern: a Papillary neo-synovium with macrophagic infiltrate and underlying vascular layer (H-E x50). b Vascular layer without lymphocytic infiltrate and cluster of particle laden macrophages, white arrow (H-E x400). Mixed macrophagic and lymphocytic pattern: c Neo-synovium with superficial macrophagic layer and desmoplastic band, white arrow, and perivascular lyphocytic infiltrate (H-E x50). d Perivascular lymphocytic infiltrate associated with large clusters of particle laden macrophages (H-E x200). Subset of the mixed pattern with heightened immunological features: e Neo-synovium with florid interstitial lymphocytic and eosinophilic infiltrate (H-E x200) and association of eosinophils with particle laden macrophages (inset, H-E x400). f Perivascular lymphocytic infiltrate with germinal center (H-E x200) associated with numerous mast cells (inset, Toluidine Blue x400). Granulomatous pattern: g Multiple sarcoid-like granulomas with central aggregate of corrosion products, white arrow (H-E x100). h Granuloma at higher power with central collection of epithelioid macrophages and occasional giant cells (H-E x200) and plasmacytic component with binucleated forms admixed with particle laden macrophages (inset, H-E x400)