Osseous and Adipocytic Differentiations in the Intraocular Lens and Vitreous

Abstract Purpose To analyze three unusual mesenchymal transformations within the eye – adipose or osseous metaplasia of the lens and adipose tissue in the vitreous cavity. Design Observational case series. Methods Re-evaluation of clinico-pathologic diagnoses and histopathologic findings in sections stained with hematoxylin and eosin, periodic acid-Schiff (PAS) reaction and Masson trichrome method. Results The three cases of mesenchymal transformation occurred in microphthalmic eyes with persistent hyperplastic primary vitreous (more recently termed persistent fetal vasculature). In one case there was total lens replacement with lamellar bone; in another total replacement of the crystalline lens by adipose tissue; and in a third an anomalous pocket of adipose tissue in the central vitreous. Multifocal remnants of the lens capsule were seen in the osseous case but were absent from the adipocytic cases. The vitreous adipose tissue was surrounded by an elaborate capillary plexus with an empty, collapsed PAS-positive lens capsule in the pupillary region. Anterior pigmented neuroectodermal disorganization, dysgenesis of angle structures and a hypoplastic or disorganized iris were also observed in the 3 cases. Conclusion After reviewing the literature, it appears that lenticular osseous replacement occurs more often than adipocytic. In addition to vascularization of the lens through a capsular dehiscence, other causes are explored, including direct epithelial-mesenchymal transformations of the lens epithelium or less likely of the disorganized adjacent neuroectoderm. The focus of vitreous adipose tissue may represent a transformed luxated lens extruded from its capsule, which was left behind in the pupillary zone.