Computerized tomographic (CT)-guided fine-needle aspiration (FNA) cytology is a well-established tool in the diagnosis of hepatic lesions. Endoscopic ultrasound-guided FNA (EUS-FNA), developed recently and used predominantly in evaluating mediastinal and pancreatic lesions, provides access to a significant portion of the liver and to perihepatic structures not readily accessible by a percutaneous approach.
A recent experience (1997-2002) with CT-guided FNA of liver lesions at the University of Alabama Birmingham (UAB) was compared with the first 2.5 years of EUS-FNA experience (2000-2002). Cases were identified using a SNOMED search and all reports and cytologic slides were retrieved for review.
In 6 years, 34 percutaneous CT-FNA liver biopsies were performed at UAB; in approximately 2.5 years, 16 EUS-FNA liver biopsies were done. In both groups the primary clinical indication was suspected metastatic carcinoma (CT, 41% of cases vs. EUS, 56%). The 2 techniques yielded a similar range of benign, atypical, and malignant diagnoses (CT: 26%, 18%, and 56% vs. EUS: 19%, 25%, and 56%). Because of the clinical setting in which EUS-FNA is usually performed, a much narrower range of neoplasms was sampled by EUS-FNA. Benign gastrointestinal epithelial cells were identified in 60% of the EUS-FNA specimens.
Early experience suggests EUS-FNA is comparable to CT-FNA in terms of diagnostic utility for hepatic lesions. Anatomy limits EUS-FNA to only a fraction of the hepatic parenchyma, but that fraction includes the hilum and left lobe of the liver and the proximal biliary tract. The gallbladder, extrahepatic biliary system, and perihilar lymph nodes are readily accessible. Proximate high-resolution ultrasound imaging and cytopathologist involvement in the EUS-FNA process are further advantages. Awareness of artifacts inherent in EUS-FNA sampling (i.e., gut epithelial cells) can minimize a potential diagnostic pitfall.