Can CD34 discriminate between benign and malignant hepatocytic lesions in fine-needle aspirates and thin core...

Distinguishing well differentiated hepatocellular carcinoma (HCC) from benign hepatocellular lesions is a well recognized problem in fine-needle aspiration (FNA) cytology. The endothelial cell marker CD34 is negative in normal hepatic sinusoids and stains vessels diffusely in HCC. This feature is useful in distinguishing benign from malignant hepatocytic lesions in histological specimens, although benign lesions may show focal positivity for CD34 confined to periportal and periseptal areas. In this study, we assess the role of CD34 in cell block and thin core biopsy material from benign and malignant hepatocellular lesions, and compare it with reticulin staining.

Cell blocks and thin core biopsies were assessed from 40 cases of HCC and 25 benign hepatocytic lesions. HCCs were scored for nuclear grade. Sections were stained for CD34 antigen and scored semi-quantitatively. Previously performed reticulin stains were reviewed.

Thirty three of 40 HCCs (82.5%) showed diffuse positivity for CD34. The other seven cases showed either focal positivity (four cases), minimal positivity (two cases) or negative staining (one case). These results did not correlate with the nuclear grade of the tumor. Two of 25 benign cases (8%) showed diffuse positivity for CD34, 8 showed focal positivity, 11 showed minimal positivity, and 4 showed negative staining. All HCCs showed an abnormal reticulin pattern characterized by expanded trabeculae and islands, or sheets, with decreased or absent reticulin. All of the benign hepatocellular lesions showed a normal trabecular reticulin pattern.

Diffusely positive CD34 staining is useful to support a diagnosis of well differentiated HCC, but in our study the reticulin stain distinguished more consistently between benign and malignant lesions.