Immunohistochemistry and electron microscopy of retrocorneal scrolls in syphilitic interstitial keratitis

Purpose: To describe the immunohistochemical and electron microscopic characteristics of retrocorneal scrolls in syphilitic interstitial keratitis. Methods: Five eyes of five patients with congenital syphilitic interstitial keratitis who underwent keratoplasty for corneal opacities and corneal edema were studied. The corneal buttons were processed for histologic examination with hematoxylin and eosin staining and underwent immunohistochemistry stainings for collagen types I, III, IV, V, VI, VIII, fibronectin, laminin, and decorin. The corneal buttons were also processed for transmission electron microscopy and immunoelectron microscopy. Results: Light microscopy revealed that the retrocorneal scrolls had a multilayered, amorphous, acellular matrix. All scrolls were lined with attenuated corneal endothelial cells. The Descemet membranes in all specimens had areas of irregular thickening with attenuated endothelium. Immunohistochemical assessment of the scrolls showed positive staining for collagens I, III, IV, VI, VIII, fibronectin, laminin, and decorin but not for α -SMA. Immunoelectron microscopy confirmed these findings. Transmission electron microscopy showed multilaminar disorganized structures in scrolls composed of long- and short-fiber collagens. Conclusions: We confirmed the presence of collagens I, III, IV, VI, VIII and proteoglycans in the retrocorneal scrolls lined with attenuated endothelium. Our findings may provide further insight into the pathogenesis of keratopathy in syphilitic interstitial keratitis.