Cytology of low-grade endocrine neoplasms involving liver: a series of 24 specimens, including 4 with hepatoid or glandular features.

Low-grade endocrine neoplasms (LGENs) involving the liver usually show typical endocrine features. Occasionally these tumors display cytologic characteristics that mimic hepatocellular carcinoma (HCC) or adenocarcinoma (ACA). Twenty-four liver FNABs from 22 patients were reviewed. Twenty specimens showed cytologic characteristics typical of LGENs, including small to medium-sized cells with salt-and-pepper or granular chromatin, moderate to high N/C ratios, and inconspicuous or absent nucleoli. Plasmacytoid cells were observed in 19 cases. Immunocytochemical stains (ICCs) confirmed endocrine differentiation in 9 cases. 4 FNABs were comprised of larger tumor cells that displayed cytologic features that overlapped with HCC or ACA, including transgressing or wrapping endothelium, moderate to abundant cytoplasm, and conspicuous nucleoli. LGENs involving the liver typically demonstrate characteristic cytologic features. Cases comprised of larger cells with abundant cytoplasm, conspicuous nucleoli, and transgressing or wrapping endothelium may pose diagnostic difficulties. ICCs and plasmacytoid morphology are beneficial in classifying the endocrine origin of these tumors.