Histopathologic changes following carmustine treatment of uveal Greene melanoma in rabbits.

Uveal Greene melanoma was produced in the anterior chamber of 47 eyes in 29 rabbits. One group of rabbits was untreated and served as controls. One group was treated with carmustine (1,3-bis(2-chloroethyl)-1-nitro-sourea; BCNU) intravenously and one group was treated with BCNU both intravenously and locally via an implanted silicone device. Tumor specimens were studied histopathologically with light and electron microscopy. Compared with controls, the treated tumors were smaller, more necrotic, and contained more spindle-shaped cells intermingled with inflammatory cells. Changes were particularly striking in the combined-treatment group. Treated tumors of both groups also showed less invasion into surrounding ocular tissues. Morphologic changes after treatment included the development of numerous degenerative tumor cells with calcium deposition, fragmentation of nuclei, degeneration of mitochondria, accumulation of fat droplets, and disorganization of cytoplasm. These changes may indicate that the drug, particularly following combined delivery, has a cytotoxic effect directly on the tumor cells.