Endoscopic ultrasound (EUS)-guided fine needles with side fenestrations are used to collect aspirates for cytology analysis and biopsy samples for histologic analysis. The investigators conducted a large, multicenter study to compare the accuracy of diagnosis via specimens collected with fine-needle biopsy (FNB) versus fine-needle aspiration (FNA) for patients with lesions requiring immunohistochemistry (IHC) pathological diagnosis.