The capability of obtaining tissue samples for histologic examination during EUS has theoretical advantages over cytology alone. The objective was to evaluate the feasibility and the yield of EUS-guided FNA tissue acquisition (EUS-FNTA) by using high negative pressure suction.

The study design is a prospective, observational pilot study set at a tertiary referral center. Twenty-seven patients with a solid mass amenable to sampling with EUS were included in the study. FNA with a 22-gauge needle was used for a total of 5 passes. An additional pass with the same needle was performed by applying continuous high negative pressure suction using the Alliance II inflation system. The main outcome measurements were the rate of tissue acquisition and the diagnostic accuracy of EUS-FNTA.

Tissue samples were obtained in 26 of the 27 patients (96%). Malignancy was detected in 20 of the 26 biopsy specimens obtained by FNTA and in 20 of the 27 FNA specimens. In 3 patients, EUS-FNTA failed to disclose malignancy, which in two of the patients was diagnosed by FNA. Conversely, EUS-FNTA diagnosed a recurrent malignant thymoma and a schwannoma in two FNA-negative patients. In 3 patients with both FNTA and FNA negative for malignancy, a definitive diagnosis could not be established. Overall, diagnostic accuracy was 76.9% for both EUS-FNTA and EUS-FNA. When combined, a correct diagnosis was achieved in 84.6% of the patients. Immunostaining of the retrieved tissue allowed characterization of the primary tumor in 5 cases and the diagnosis of a schwannoma and two neuroendocrine tumors. Limitations of the study were small sample size and a pilot study.

EUS-FNTA has a high yield for the retrieval of core tissue samples. Further studies in which EUS-FNTA is performed before FNA and with variable number of passes are needed to better define its diagnostic role and performance characteristics.