1.North Shore University Hospital, Long Island Jewish Medical Center, Hofstra University School of Medicine, New York, USA
Microscopically, NSETs are characterized by organoid arrangement of cellular nests composed of spindle and epithelioid cells embedded in a desmoplastic or fibrocytic/myofibroblastic stroma, within which proliferation of bile ductules is noted. Areas of myxoid and cystic degeneration or necrosis are sometimes encountered within or adjacent to the cellular nests. Focal psammomatous calcification or osteoid formation is present in some tumors. Lymphovascular invasion is occasionally seen. The spindle cells within the cellular nests are arranged in short fascicles with a somewhat whorled pattern. The nested cells are characterized by plump nuclei, stippled chromatin, and inconspicuous nucleoli. Scattered mitotic figures with abnormal forms are identified.
Immunohistochemically, the tumor cells are stained positive for cytokeratin AE1/AE3, keratin CK19 (focal), EMA, CD117 (c-kit), CD56, CD99, ACTH, chromogranin, synaptophysin, neuron-specific enolase, and S100 (focally weak in epithelioid cells). Vimentin stain is positive in the nested spindled cell and stroma. Muscle specific actin and smooth muscle actin immunostains highlight stromal myofibroblastic cells. Alpha-fetoprotein and p53 are negative.
Y Albert Yeh
Liver: Nested stromal epithelial tumor
Atlas Genet Cytogenet Oncol Haematol. 2010-04-01
Online version: http://atlasgeneticsoncology.org/solid-tumor/6243/gene-fusions-explorer/