Endoscopic ultrasound-guided, 18-gauge, fine needle aspiration biopsy of the pancreas using a 2.8 mm channel convex array echoendoscope

Background: Previous studies have reported on endoscopic ultrasound-guided, fine needle aspiration biopsy using 22- to 25-gauge needles. We evaluated the histologic and cytologic yield of endoscopic ultrasound-guided, fine needle aspiration biopsy of the pancreas using an 18-gauge, Menghini-type core needle. Methods: Fine needle aspiration biopsy was performed in conjunction with a prototype 2.8 mm channel convex array echoendoscope. The core specimen was placed in formalin for cell block, and residual material was expelled on slides for cytology. Definitive diagnosis was established by surgery or clinical follow-up. Results: Of 45 patients who underwent fine needle aspiration biopsy, the needle failed to penetrate indurated pancreatic lesions in five. An average of 2.6 passes were performed in the remaining patients. Sufficient material for a histologic and/or cytologic diagnosis was obtained in 40 patients (histologic and cytologic yield of 68% and 75%, respectively). Combining the results of histology and cytology, the sensitivity and specificity for detection of malignancy was 76% and 100%, respectively. Histology confirmed the cytologic findings in 35 patients, providing additional tissue specific information. In three cases histology established a diagnosis of malignancy where cytology was not conclusively malignant. However, in three cases of surgically confirmed malignancy histology failed to detect malignancy, whereas cytology showed suspicious or malignant cells. The sensitivity of histology and cytology alone in detecting malignancy was 53% and 70%, respectively. Mild pancreatitis occurred after pancreatic fine needle aspiration biopsy in one patient. Conclusion: Core specimens for histology can be safely obtained using an 18-gauge needle. Histology provides tissue-specific information that complements cytology, but histology is less sensitive than cytology in detecting malignancy.