Renal interstitial cell tumor (RICT) is a rare renal sarcoma of dogs that arises from renal interstitial cells. Herein we describe a RICT in an 8-y-old female Labrador Retriever dog that died after a 2-d history of lethargy and disorientation. Grossly, soft white nodules of 1–10 mm diameter were present in the renal cortex and corticomedullary junction of both kidneys, left cardiac ventricular wall, and right cerebral hemisphere. A pale-white to yellow, firm, irregular mass effaced 80% of the right pulmonary parenchyma, involving mainly the cranial and middle lobes, and the adjacent tracheobronchial lymph nodes. Histologically, the renal, myocardial, and cerebral neoplasm consisted of interlacing bundles of stellate-to-spindle cells with eosinophilic vacuolated cytoplasm and round-to-oval nuclei with finely stippled chromatin. The mitotic count was 28 per 2.37 mm². Alcian blue stain revealed an extracellular myxomatous matrix throughout the neoplasm. Neoplastic cells had cytoplasmic immunolabeling for vimentin and cyclooxygenase 2. The pulmonary and tracheobronchial neoplasm consisted of infiltrative nodules of cuboidal epithelial cells that had a moderate amount of eosinophilic cytoplasm and round nuclei with coarsely stippled chromatin. There were 5 mitoses per 2.37 mm². Neoplastic cells had cytoplasmic and nuclear immunolabeling for cytokeratin AE1/AE3 and thyroid transcription factor 1, respectively. Morphologic and immunohistochemical findings were consistent with a RICT with cardiac and cerebral metastases, and a pulmonary carcinoma with tracheobronchial lymph node metastasis.

肾间质细胞瘤 (RICT) 是一种罕见的犬肾肉瘤，起源于肾间质细胞。在本文中，我们描述了 8 岁雌性拉布拉多犬的 RICT，该犬在 2 d 嗜睡和迷失方向后死亡。大体上，双肾的肾皮质和皮质髓质连接处、左心室壁和右大脑半球存在直径 1-10 mm 的软白色结节。淡白色至黄色、坚硬、不规则的肿块消失了 80% 的右肺实质，主要累及颅和中叶，以及相邻的气管支气管淋巴结。组织学上，肾、心肌和脑肿瘤由星状到纺锤形细胞的交错束和嗜酸性空泡细胞质和圆形到椭圆形的细胞核组成，细胞核有细点状染色质。² . 阿尔新蓝染色显示整个肿瘤中存在细胞外粘液瘤基质。肿瘤细胞具有波形蛋白和环加氧酶 2 的细胞质免疫标记。肺和气管支气管肿瘤由立方上皮细胞的浸润性结节组成，具有中等数量的嗜酸性细胞质和圆形核，染色质粗点状。每 2.37 mm ²有 5 个有丝分裂。肿瘤细胞分别对细胞角蛋白 AE1/AE3 和甲状腺转录因子 1 进行细胞质和核免疫标记。形态学和免疫组织化学结果与具有心脏和脑转移的 RICT 以及具有气管支气管淋巴结转移的肺癌一致。