Misinterpretation of normal cellular elements in fine-needle aspiration biopsy specimens: Observations from the College of American Pathologists Interlaboratory Comparison Program in Non-Gynecologic Cytopathology

Context. - The College of American Pathologists Interlaboratory Comparison Program in Non-Gynecologic Cytopathology is a popular educational program for nongynecologic cytology, with 1018 participating laboratories by the end of 2000. Data generated from this program allow tracking pathologist performance in a wide variety of laboratory practices. Objective.-To review performance of participating pathologists in making patient diagnoses with fine-needle aspiration biopsy specimens, with particular interest in the false neoplastic diagnoses (both benign and malignant neoplasms) that were submitted for benign aspirates containing only normal cellular components. Design. - We reviewed the diagnoses made from 1998 through 2000 by participating pathologists through the use of glass slides containing benign fine-needle aspiration biopsy specimens of the liver, kidney, pancreas, and salivary gland that contained only normal cellular components. Results. - The false neoplastic rate for kidney (60%) was the highest, followed by liver (37%), pancreas (10%), and salivary gland (6%). These rates are much higher than what has previously been reported in the literature. Conclusions. - This study illustrates that normal cellular elements are a significant pitfall for overinterpretation of fine-needle aspiration biopsy specimens.