Spontaneous intaocular amelanotic melanomas in ktc:Sprague-Dawley rats

Kang, Boo-hyon; Son, Hwa-young; Ha, Chang-su; Kim, Dae-yong

Korean Journal of Veterinary Research 1995;35(2):375-381.

Boo-hyon Kang¹, Hwa-young Son¹, Chang-su Ha¹, Dae-yong Kim²

¹Korea Research Institute of Chemical Technology
²Louisiana State University

Ktc:Sprague-Dawley 랫드의 안구에 자연발생한 amelanotic melanoma

강부현¹, 손화영¹, 하창수¹, 김대용²

¹한국화학연구소
²Louisiana 주립대학교

Abstract

Two intraocular tumors were identified in low and medium dosed groups of a carcinogenicity study using 200 males and 200 females Sprague-Dawley rats in Screening & Toxicology Research Center, Korea Research Institute of Chemical Technology. The tumors were grossly observed as white or yellow, unilateral nodules. They were approximately $1-2{ imes}3-5mm$ in size. The tumors located in the region of iris and/or ciliary body invaded peripheral cornea. The microscopic features were usually composed of spindle cells arranged in parallel, forming gently curving bundles or whorls. The spindle cells had poorly defined cell boundaries, scant to moderate cytoplasm, fusiform nuclei and indistinct nucleoli. Mitotic figures were rare and areas of necrosis were present. The spindle cells had positive immunoreactivity for S-100 protein and vimentin but negative for desmin, collagen and HMB-45 antibody. In special histochemical studies, the spindle cells react with Gomori's stain for argyrophih fibers, Prussian blue stain for iron but negative with Masson-Fontana's stain for melanin granules. Ultrastructurally, cytoplasmic premelanosomes were not observed in the tumor cells due to the poor preservation of tumor masses. Based on the results, the tumors were diagnosed as amelanotic melanoma.

Key Words: amelanotic melanoma, immunohistochemistry, Sprague-Dawley rats