Utility of CD34 reactivity in evaluating focal nodular hepatocellular lesions sampled by fine needle aspiration biopsy

OBJECTIVE: To determine the patterns of CD34 reactivity ill hepatocellular adenoma and focal nodular hyperplasia and to evaluate the utility of CD34 reactivity in the diagnosis of hepatocellular carcinoma. STUDY DESIGN: Seventeen cases of well-differentiated hepatocellular carcinoma, 14 cases of cirrhosis, 9 cases of focal nodular hyperplasia and 7 cases of hepatocellular adenoma were stained with immunoperoxidase antibodies to CD34. The slides were scored according to the degree of lesional activity. RESULTS: Fourteen of 17 cell blocks with hepatocellular carcinoma showed unequivocal sinusoidal or peripheral reactivity for CD34. Five of seven cases of hepatocellular adenoma and four of nine cases of focal nodular hyperplasia showed >50% sinusoidal reactivity for CD34. All 14 cases of cirrhosis showed peripheral to no sinusoidal reactivity. CONCLUSION: CD34 reactivity in a diffuse sinusoidal pattern can be helpful in the diagnosis of hepatocellular carcinoma. However, consideration should be given to the possibility of hepatocellular adenoma and focal nodular hyperplasia, which call also exhibit significant diffuse CD34 reactivity. In these discs, a reticulin stain may be helpful with the differential diagnosis.