Fine needle aspiration (FNA)
Fine needle aspiration (FNA) is used mainly for the diagnosis of focal lesions of the liver, whereas percutaneous biopsy with a large-core needle is preferred for diagnosing diffuse liver diseases (such as hepatitis and cirrhosis), for which architectural details are important.
Sensitivity of cytology is higher than the one of histology, whereas histology is more specific. The combination of both techniques allows a higher sensitivity and a more precise definition of the lesion.
FNA is usually performed percutaneously under the guidance of computed tomography (CT), magnetic resonance imaging (MRI) or ultrasonography. It is a very sensitive and specific method in diagnosing malignancies. False positive results are vey rare. FNA cannot differentiate hepatic adenoma, focal nodular hyperplasia and regenerative nodules in cirrhosis, but it is useful in these cases for excluding a malignancy.
US-guided FNA can also be used to obtain material for diagnosing tumors of the hilum of the liver, even if endoscopic retrograde cholangiopancreatography (ERCP) with brushing is the preferred technique in these cases, and it has also been used in the monitoring of liver transplants for acute cellular rejection.
Complications of FNA are rare, including hemorrhage, bile peritonitis, tumor seeding, anaphylactic shock (after aspiration of an echinococcal cyst).