Biopsy diagnosis of malignant versus benign liver "nodules": new helpful markers. An update.

Improved imaging techniques have led to an increased detection of suspicious "nodules" in the cirrhotic and noncirrhotic liver. Although the histologic diagnosis of clearly benign or clearly malignant lesions is usually straightforward, problems arise in the differential diagnosis of benign "nodules" and dysplastic lesions or well-differentiated hepatocellular carcinomas. This is especially so in limited diagnostic material, such as cytologic preparations from fine-needle aspirates and needle-core tissue biopsies. Recently, additional helpful markers have been described that may help to establish a conclusive diagnosis even on such material. Two of these, the reticulin stain and immunohistochemical staining for CD34, have been found to be useful also in cytologic cellblock material. Telomerase, a complex enzyme that is active in most malignant tumors, has also been found to show strong activity in most hepatocellular carcinomas. Mention is made of an immunohistochemical marker (MOC-31), reported to be useful in the differentiation between metastatic adenocarcinoma and hepatocellular carcinoma.