A 10-year-old spayed female Border Collie developed a ductal adenocarcinoma in the spleen. Clinically, the spleen was enlarged and a small liver nodule was present but there were no other abnormalities. Most of the splenic parenchyma was diffusely infiltrated by variably shaped atypical neoplastic cells that formed small clusters or larger nests, arranged as duct or duct-like structures within a fibrous matrix. There was acinar differentiation in a few portions of the tumour with a sheet-like solid growth pattern and occasional squamous metaplasia or exocrine acinus-like structures. Mitotic figures were frequent. Neoplastic cells with ductal differentiation were diffusely immunoreactive for AE1/AE3, CAM5.2 and CK7 cytokeratins but negative for CK20, while cells with acinar differentiation were immunolabelled only for AE1/AE3 cytokeratins and were also immunopositive for mucin-1 and trypsin. A few regions of tumour with ductal or acinar differentiation were immunopositive for pancreatic lipase. All neoplastic cells were negative for mucin-2, vimentin, smooth muscle actin, chromogranin A, CD31, hepatocyte paraffin 1 and thyroglobulin antigens. Because of the formation of exocrine acinus-like structures and an immunolabelling pattern consistent with exocrine pancreas tissue, an adenocarcinoma of ectopic exocrine pancreas within the spleen was diagnosed.

一只 10 岁的绝育雌性边境牧羊犬在脾脏中发生了导管腺癌。临床上脾脏肿大，肝脏有小结节，但无其他异常。大多数脾实质被形状各异的非典型肿瘤细胞广泛浸润，形成小簇或较大的巢，在纤维基质内排列为导管或导管样结构。肿瘤的少数部分有腺泡分化，呈片状实性生长模式，偶见鳞状上皮化生或外分泌腺泡样结构。有丝分裂的数字很常见。具有导管分化的肿瘤细胞对 AE1/AE3、CAM5.2 和 CK7 细胞角蛋白呈弥漫性免疫反应，但对 CK20 呈阴性，而具有腺泡分化的细胞仅对 AE1/AE3 细胞角蛋白进行免疫标记，并且对粘蛋白 1 和胰蛋白酶也呈免疫阳性。一些具有导管或腺泡分化的肿瘤区域对胰脂肪酶呈免疫阳性。所有肿瘤细胞的粘蛋白 2、波形蛋白、平滑肌肌动蛋白、嗜铬粒蛋白 A、CD31、肝细胞石蜡 1 和甲状腺球蛋白抗原均为阴性。由于外分泌腺泡样结构的形成和与外分泌胰腺组织一致的免疫标记模式，诊断出脾内异位外分泌胰腺的腺癌。CD31、肝细胞石蜡 1 和甲状腺球蛋白抗原。由于外分泌腺泡样结构的形成和与外分泌胰腺组织一致的免疫标记模式，诊断出脾内异位外分泌胰腺的腺癌。CD31、肝细胞石蜡 1 和甲状腺球蛋白抗原。由于外分泌腺泡样结构的形成和与外分泌胰腺组织一致的免疫标记模式，诊断出脾内异位外分泌胰腺的腺癌。