Endoscopic ultrasound-guided fine-needle biopsy in patients with unexplained diffuse gastrointestinal wall thickening

Background and study aims  Endoscopic ultrasound-guided fine needle biopsy (EUS-FNB) is recommended after non-diagnostic biopsy in gastrointestinal wall thickening, although the performance of currently available FNB needles in this setting is unknown. We aimed to assess the diagnostic accuracy and safety of EUS-FNB and to evaluate the "T" wall staging in malignant pathology. Patients and methods  This was a single center retrospective study that included all consecutive patients undergoing EUS-FNB for diffuse gastrointestinal wall thickening with at least one previous negative conventional endoscopic biopsy between January 2016 and November 2019. EUS-FNB was performed using linear-array echoendoscopes with slow-pull/fanning technique. Tissue acquisition was done with 19- or 22-gauge biopsy needles. Samples were included in formalin without rapid on-site evaluation and submitted for histopathological processing. The final diagnosis was based on conclusive histology or absence of evidence of disease progression after follow-up at least 6 months. Results  Twenty-nine patients (21 men), with a median age of 68 (IQR: 56-77), were included. EUS-FNB was technically feasible and the sample quality was adequate for full histological assessment in all patients (100 %). Sensitivity, specificity, positive and negative predictive values, and overall accuracy for diagnosis of malignancy were 95.5 %, 100 %, 100 %, 83.3 %, and 96.3 %, respectively. In patients with malignant disease, the samples obtained allowed detection of signs of deep layer infiltration ("histological staging") in 17 of 21 cases (81 %). No adverse events were noted. Conclusions  The EUS-FNB technique demonstrated excellent diagnostic performance and safety in the study of unexplained diffuse gastrointestinal wall thickening. Histological staging was obtained in a high percentage of samples.