Zhang Zesong, Lee John G, Gu Mai
Department of Pathology & Laboratory Medicine, University of California Irvine Medical Center, Orange, California.
Diagn Cytopathol. 2014 Apr;42(4):308-13. doi: 10.1002/dc.23009. Epub 2013 Jun 8.
Pancreatic endocrine tumor (PET) is an uncommon neoplasm of the pancreas with distinct cytomorphologic features. Lipid-rich PET, a rare variant, histologically deviates from that of a conventional PET. There is only one case report of the cytologic features of this rare entity in the literature. We report two cases of lipid-rich PETs diagnosed by endoscopic ultrasound-guided FNA biopsy. Case 1 showed large aggregates, small clusters, and single cells with plasmacytoid appearance, small uniform nuclei, coarse chromatin, and prominent nucleoli. Abundant distinct small cytoplasmic vacuoles were present in almost all tumor cells and the background was clean. Case 2 showed flat cohesive sheets of medium-sized uniform cells with indistinct plasmacytoid appearance, uniform nuclei, fine and evenly distributed chromatin, and inconspicuous nucleoli. Distinct small cytoplasmic vacuoles were seen only focally. Immunohistochemical stains in cell blocks of both cases confirmed the diagnosis of PET. Lipid-rich PET may be misinterpreted on cytology specimens if the pathologist is not aware of this rare entity since it mimics clear cell carcinoma of the kidney, adrenal cortical neoplasm, or adenocarcinoma of the pancreas.
胰腺内分泌肿瘤（PET）是一种胰腺的罕见肿瘤，具有独特的细胞形态学特征。富含脂质的PET是一种罕见的变异型，其组织学特征与传统PET不同。文献中仅有一篇关于这种罕见实体细胞特征的病例报告。我们报告两例经内镜超声引导下细针穿刺活检诊断为富含脂质PET的病例。病例1显示有大的细胞团、小细胞簇以及具有浆细胞样外观、小而均匀的细胞核、粗糙染色质和明显核仁的单个细胞。几乎所有肿瘤细胞中都有大量明显的小细胞质空泡，背景干净。病例2显示由中等大小均匀细胞组成的扁平黏附片，浆细胞样外观不明显，细胞核均匀，染色质细腻且分布均匀，核仁不明显。仅在局部可见明显的小细胞质空泡。两例病例细胞块的免疫组化染色均确诊为PET。如果病理学家不了解这种罕见实体，富含脂质的PET在细胞学标本上可能会被误诊，因为它可模仿肾透明细胞癌、肾上腺皮质肿瘤或胰腺腺癌。
