含有色素和光反射的细胞肿瘤，通常称为色素瘤，影响鱼类、爬行动物和两栖动物。光反射细胞的色素瘤被称为虹彩色素瘤。在这项研究中，我们旨在描述 71 例养殖暹罗斗鱼（Betta splendens）虹膜瘤病例的大体、组织学和超微结构发现。从宏观上看，虹彩细胞瘤表现为鱼鳍、躯干/尾部或头部的白色、灰色或黑色易碎团块或斑块。 45 个肿瘤 (63%) 是恶性的，并侵犯邻近的骨骼肌和/或转移到其他器官，而 26 个肿瘤 (37%) 仅限于皮肤，但由于与恶性对应物的细胞学相似性，我们无法将它们分类为恶性或良性。 65 例 (91%) 肿瘤被归类为虹彩细胞瘤，而 6 例 (8%) 被诊断为混合色素瘤。尽管 PNL-2、melan A 或 S-100 的免疫标记未能证明抗原表达，但超微结构分析鉴定出反光肿瘤细胞，明确证实虹彩细胞瘤是主要肿瘤。来自同一养殖设施的暹罗斗鱼中虹彩细胞瘤的高发病率，加上宝蓝色和花式铜色图案以及年轻雄性的发病率较高，表明这些肿瘤的肿瘤发生中存在潜在的遗传/遗传因素。

Pigment-containing and light-reflecting cell neoplasms, generically termed chromatophoromas, affect fish, reptiles, and amphibians. Chromatophoromas of light-reflecting cells are named iridophoromas. In this study, we aimed to describe the gross, histologic, and ultrastructural findings of 71 cases of iridophoromas in farmed Siamese fighting fish (Betta splendens). Macroscopically, iridophoromas appeared as whitish, gray, or black friable masses or plaques in the fin, trunk/tail, or head of the fish. Forty-five tumors (63%) were malignant and invaded the adjacent skeletal muscle and/or metastasized to other organs, whereas 26 (37%) tumors were restricted only to the skin, but due to the cytologic similarity to the malignant counterpart, we were not able to classify them as malignant or benign. Sixty-five (91%) tumors were classified as iridophoromas, whereas 6 (8%) were diagnosed as mixed chromatophoromas. Despite immunolabeling for PNL-2, melan A, or S-100 failing to demonstrate antigen expression, ultrastructural analysis identified light-reflecting neoplastic cells, unequivocally confirming iridophoromas as the predominant tumor. The high incidence of iridophoromas in Siamese fighting fish from the same breeding facility, coupled with a higher occurrence in royal blue and fancy copper color patterns and in young males, suggests a potential genetic/hereditary factor in the tumorigenesis of these neoplasms.