Overview and evaluation of the value of fine needle aspiration cytology in determining the histogenesis of liver nodules: 14 years of experience at Hannover Medical School.

Fine needle aspiration (FNA) is a sensitive and specific method (95%), often helpful in characterizing suspected liver lesions. It is appropriate to distinguish between primary and secondary liver neoplasia. Moreover, in most cases, the use of cell block preparations of small specimens allows immunocytochemical evaluation to determine the nature of the primary tumour. In a retrospective study at Hannover Medical School (MHH) from 1998 to 2012 (14 years), 4,136 sonographically guided FNAs were performed. The patients provided consent and the study protocol was approved by the local ethics committee. There were 39.6% malignant and 57.5% benign lesions in the liver, while 2.8% of the cases were undetermined. FNA was non-representative in 1.1% of the cases. The diagnostic utility of highly differentiated hepatocellular carcinoma (HCC; G1) remains difficult; cell bridges with cell atypia are pathognomonic for diagnosis. Ancillary techniques and immunocytochemical investigations will increase the sensitivity and specificity, particularly by using the cell block technique.