Terayama Yui, Matsuura Tetsuro, Ozaki Kiyokazu
Laboratory of Pathology, Faculty of Pharmaceutical Sciences, Setsunan University, 45-1 Nagaotoge-cho, Hirakata, Osaka 573-0101, Japan.
J Toxicol Pathol. 2017 Jan;30(1):63-67. doi: 10.1293/tox.2016-0044. Epub 2016 Oct 10.
A 152-week-old male Royal College of Surgeons (RCS) rat kept as a non-treated animal in a long-term animal study presented with a soft mass in the anterior mediastinum, which adhered to the pleura of the lung. Histopathologically, the mass mainly consisted of round to short spindle-shaped tumor cells that had infiltrated through the hyperplastic thymic tissue. The tumor cells were arranged in loose to dense sheets. Nuclei were moderate in size and round to spindle-shaped, with small nucleoli. Almost all tumor cells exhibited abundant eosinophilic cytoplasm, including eosinophilic granules of a range of sizes. The granules of tumor cells exhibited metachromasia with toluidine blue stain and were positive for c-kit and mast cell protease II. These findings indicate that the tumor described here represents a rare case of spontaneous malignant mast cell tumor with thymic epithelial hyperplasia.
在一项长期动物研究中，一只152周龄的雄性皇家外科学院（RCS）大鼠作为未治疗动物饲养，其前纵隔出现一个软组织肿块，该肿块与肺胸膜粘连。组织病理学上，肿块主要由圆形至短梭形肿瘤细胞组成，这些细胞浸润穿过增生的胸腺组织。肿瘤细胞呈松散至致密的片状排列。细胞核大小适中，呈圆形至梭形，有小核仁。几乎所有肿瘤细胞都表现出丰富的嗜酸性细胞质，包括一系列大小的嗜酸性颗粒。肿瘤细胞的颗粒经甲苯胺蓝染色显示异染性，且c-kit和肥大细胞蛋白酶II呈阳性。这些发现表明，此处描述的肿瘤是一例罕见的伴有胸腺上皮增生的自发性恶性肥大细胞瘤。
