Endoscopic Ultrasound-Guided Fine-Needle Aspiration

As a diagnostic medium, cytology historically has come in waves, as reflected in its published literature. Several of these were rapidly propagated by technical advances. Most of us do not remember when Papanicolaou (Pap) smears were new (they were not always called Pap tests). Invention of the first cytocentrifuge made possible recognition of central nervous system disease in acute leukemia and revolutionized treatment of that condition, especially in children. Now largely routine, the fine-needle aspiration (FNA) wave buoyed a number of important careers and left some real changes in the practice of medicine. The ascendancy of bronchoalveolar lavage was contemporaneous with the AIDS epidemic and facilitated rapid, accurate diagnosis of pneumonias due to a variety of infectious agents. On the other hand, its early promise regarding classification, grading, and staging of inflammatory pulmonary disease has gone largely unfulfilled; except for the eosinophilic pneumonias, we now rarely field questions about the immune-effector cell content of such samples. Currently, endoscopic ultrasound (EUS)-guided FNA is rapidly revolutionizing our diagnostic approach to masses in the upper gastrointestinal tract, pancreas, liver, left adrenal gland, and mediastinum.1 In this issue of the Journal, Jhala and colleagues1 describe their experience with this method and offer guidance to those preparing to implement such testing. I agree with these authors that EUS-guided FNA quickly will become the diagnostic approach of choice for many mass lesions in these sites. These authors provide a review of EUS-guided FNA as it is applied to a number of body sites. However, its most frequent application is to masses or to more enigmatic enlargements in the pancreas, and it is this organ that will largely form the basis for this commentary. When pancreatic ductal adenocarcinoma (PDA) is considered, EUS can provide detailed staging information. Enlarged regional lymph nodes or hepatic lesions can be visualized and sampled during the same procedure that confirms carcinoma in the pancreas itself. Ultrasound can demonstrate invasion of major vascular structures, providing further evidence that surgery is contraindicated. In the case of chronic pancreatitis, often the most important differential diagnostic consideration, clinical and sonographic impressions can be supported by cytologic findings that are benign and inflammatory, albeit occasionally atypical. One of the big surprises has been that intraductal papillary mucinous neoplasms (IPMNs) probably are much more common than any of us had heretofore guessed. Many examples of IPMN occur in older people with comorbid conditions; surgical follow-up frequently is not forthcoming.2 These clinical considerations take cytology in directions that may be new for some. One must marry clinical, EUS, and cytologic findings to achieve the most accurate possible assessment of a patient’s condition. Many laboratory diagnoses, both benign and malignant, will not have surgical follow-up. This is especially true for cases of PDA, in which EUS demonstrates staging information with evidence of advanced disease, and for many cases of IPMN. Such is the nature of advanced pancreatic disease; cytology, united with all available clinical and imaging information, must truly stand on its own. Based on these considerations, I agree with Jhala and coworkers1 that a cytopathology presence in the endoscopy suite is essential for optimal application of EUS-guided FNA. In many institutions, much of the time required for this presence may be fulfilled by an advanced trainee for all but