Diagnostic value of HepPar1, pCEA, CD10, and CD34 expression in separating hepatocellular carcinoma from metastatic carcinoma in fine‐needle aspiration cytology

Differentiating primary and metastatic hepatic malignancies can be diagnostically challenging in fine‐needle aspiration cytology (FNAC). We compared four immunohistochemical (IHC) markers, pCEA, CD10, HepPar1, and CD34, in differentiating hepatocellular carcinoma (HCC) from metastatic carcinoma (MC) in FNAC specimens. Sixty cases of liver FNAC with their corresponding cell blocks were retrieved from the hospital computer system, including 30 HCC and 30 MC (15 colon, 10 breast, and 5 pancreas). The diagnoses were confirmed by clinical follow‐up and surgical resection or core needle biopsy. The direct cytologic smears were air‐dried and Diff‐Quik‐stained, and alcohol‐fixed and Papanicolaou‐stained. Cell block sections from the aspirates were immunostained for pCEA, CD10, HepPar1, and CD34. IHC on cytologic smears for HCC was performed on 10 cases and compared with the cell block results. In HCC, CD10, and pCEA demonstrated the characteristic canalicular staining in 23/30 (77%) and 24/30 (80%) of the cases, respectively; however, none of the MC showed a canalicular staining pattern. HepPar1 was positive in 26/30 (87%) of the HCC cases and one MC. CD34 stained sinusoidal endothelial cells in 27/30 (90%) cases of HCC and six MC. Our results demonstrate that the canalicular staining pattern for CD10 and sinusoidal staining pattern of CD34 are very specific, in addition to the high specificity and sensitivity of HepPar1 for HCC. Cell blocks were more informative in demonstrating the characteristic architecture and immunostaining pattern of the malignancy than the cytologic smears. An IHC panel consisting of pCEA, CD10, HepPar1, and CD34 is useful for confirming HCC in FNAC of the liver. Diagn. Cytopathol. 2004;30:1–6. © 2004 Wiley‐Liss, Inc.