Background Endoscopic Ultrasound-Guided Tissue Acquisition (EUS-TA) has become the mainstay for tissue diagnosis of abdominal mass lesions. Two widely used and accepted methods for obtaining diagnostic material, fine needle aspiration cytology (EUS FNAC) and needle core biopsy (EUS FNB), have distinct advantages and disadvantages. We compared the diagnostic accuracy of EUS FNAC and EUS FNB in solid gastrointestinal and extra-intestinal abdominal masses.

Methods In this prospective observational study, we included patients undergoing EUS FNAC and EUS FNB for the diagnosis of solid intra-abdominal masses. The sample size was calculated based on the available literature. Location, origin, dimensions of intraabdominal masses and number of passes taken were recorded. The adequacy of the FNB specimen was judged visually, while the adequacy of the FNA was judged under a microscope. Histological diagnosis from FNB specimens was considered standard to assess the diagnostic accuracy of EUS FNA.

Results Of the 58 patients included, 50% of patients were females with a mean age of 53.91±17.16 years.19 pancreatic masses (32.7%), 3 gastric mass lesions (5.1%),1 adrenal mass (1.7%),1 liver mass (1.7%),3 gallbladder masses (5.1%), and 31 lymph node masses (53.4%) were sampled. The sample was found to be adequate for reporting in all patients. The sample was adequate in all specimens. With EUS FNB, malignancy was diagnosed in 33/58 (56.8%), benign diseases in 24/58 (41.3%), and 1/58(1.7%) were inconclusive. The number of passes was more in the EUS FNA group compared to EUS FNB, but not statistically significant. The sensitivity and specificity of EUS FNA were found to be 92.4% and 100%, respectively. The diagnostic accuracy of EUS FNA was 93.1% and when compared with EUS FNB and no statistically significant difference was noted.

Conclusions EUS FNA is comparable to EUS FNB for the diagnosis of intrabdominal masses in terms of diagnostic accuracy, sample adequacy, number of passes, and safety. In resource-constraint settings, FNA alone may be sufficient for diagnosis, with EUS FNB reserved for cases needing immunohistochemistry.