Nakashima N, Takahashi K, Harada T, Maita K
Toxicology Division, Institute of Environmental Toxicology, Japan.
Toxicol Pathol. 1996 Mar-Apr;24(2):258-61. doi: 10.1177/019262339602400215.
An epithelioid cell type of spontaneous amelanotic melanoma in the pinna of an aged albino Fischer-344 (F-344) rat is described. When the rat was necropsied at 109 wk of age, the pinnal tumor was recognized as a white spherical mass of 4 mm in diameter. Histologically, the tumor was observed in the dermis and composed of large round or polyhedral epithelioid eosinophilic cells that were arranged in various-sized cell nests. Immunohistochemistry demonstrated that the tumor cells were positive for S-100 protein and vimentin but negative for keratin and a rat macrophage antigen. Ultrastructurally, a few single membrane-bound premelanosomes that were accompanied by many primary lysosome-like bodies containing very fine granules were present in the cytoplasm of the tumor cells. This study has disclosed that, in addition to spindle cell variants of amelanotic melanomas, an epithelioid cell type of amelanotic melanoma may occur spontaneously in the skin of F-344 rats.
描述了一只老年白化病Fischer-344（F-344）大鼠耳廓中自发的无色素性黑色素瘤的上皮样细胞类型。当这只大鼠在109周龄时进行尸检时，耳廓肿瘤被识别为一个直径4毫米的白色球形肿块。组织学上，肿瘤见于真皮，由大的圆形或多面体上皮样嗜酸性细胞组成，这些细胞排列成大小不一的细胞巢。免疫组织化学显示肿瘤细胞S-100蛋白和波形蛋白呈阳性，但角蛋白和大鼠巨噬细胞抗原呈阴性。超微结构上，肿瘤细胞的细胞质中存在一些单个膜结合的前黑素小体，伴有许多含有非常细颗粒的初级溶酶体样小体。这项研究表明，除了无色素性黑色素瘤的梭形细胞变体之外，无色素性黑色素瘤的上皮样细胞类型可能在F-344大鼠的皮肤中自发发生。
