Diagnostic utility of CD10 in differentiating hepatocellular carcinoma from metastatic carcinoma in fine-needle aspiration biopsy (FNAB) of the liver.

The differential diagnosis between hepatocellular carcinoma (HCC) and metastatic carcinoma, especially in moderate-poorly differentiated (MPD) HCC and poorly differentiated carcinoma, can be challenging in fine-needle aspiration biopsy (FNAB) of the liver. Recent studies demonstrate that canalicular staining for CD10 appears to be a highly specific marker for hepatocytic differentiation. The objective of this study was to test the utility of CD10 in differentiating HCC from metastatic carcinoma in FNAB of the liver. Formalin-fixed, paraffin-embedded cell blocks of 55 cases (22 HCC, 23 metastases, and 10 benign hepatic lesions) of FNAB of the liver were immunostained using monoclonal antibody against CD10, with microwave oven antigen retrieval, followed by a standard ABC method. Nineteen (86%) of 22 HCC cases were positive for CD10 with a canalicular staining pattern. Among them, 9 (82%) of 11 well-differentiated (WD) HCC and 10 (91%) of 11 MPD HCC were positive for CD10. Three (13%) of 23 metastatic carcinomas were positive for CD10, demonstrating a contrasting cytoplasmic and membranous staining pattern. The three positive cases were metastatic renal cell carcinoma (RCC), choriocarcinoma, and adenocarcinoma of the lung. All 10 cases of benign hepatic lesions showed positivity for CD10 with a canalicular and focal membranous staining pattern. In conclusion, CD10 appears to be a useful marker in discriminating between HCC and metastatic carcinoma when applied to FNAB of the liver. CD10 does not provide discrimination between WD HCC and benign hepatocytes.