BACKGROUND: The importance of interinstitutional consultation (IC) has been documented across a variety of surgical pathology organ systems. However, to the authors' knowledge, few studies exist regarding this practice within cytopathology and specifically within fine‐needle aspiration cytology (FNAC). METHODS: All FNAC cases between September 2002 and January 2007 were reviewed. Original diagnoses and second opinion diagnoses (SODs) were categorized as either no diagnostic disagreement, or minor diagnostic disagreement, or major diagnostic disagreement, and the latter was defined as either a 2‐step deviation on a scale of “unsatisfactory, benign, atypical, suspicious, and malignant” or a change in treatment and/or prognosis. Outcome was determined by a review of the electronic medical record. RESULTS: Among 742 FNAC cases from outside laboratories, there were minor disagreements in 132 cases (17.8%) and major disagreements in 69 cases (9.3%) compared with the SODs from the authors' laboratory. Follow‐up was available for 60 of 69 major discrepancies. The SOD was supported on follow‐up in 65% of major discrepancies, and the initial diagnosis was supported better in 33% of major discrepancies. In 55% of cases in which the original institution diagnosis was supported better, either no case slides were received for examination or the slides contained material that was considered nondiagnostic by the authors. An SOD prompted a change in clinical management in 32 of 742 patients (4.3%). Aspirates that were most prone to change in management or therapy were from the thyroid (13 cases), neck (soft tissue and lymph nodes; 9 cases), salivary gland (2 cases), and liver (2 cases). Of 60 major diagnostic disagreements, board‐certified cytopathologists rendered an SOD in 44 cases, and 75% of the diagnoses were supported better by follow‐up, whereas pathologists who were not board certified in cytopathology had only 38% of SODs supported. CONCLUSIONS: Of 742 FNAC cases, 9.3% had major diagnostic disagreements; and, in 4.3%, patient management and therapy were altered. These results were similar to studies in surgical pathology emphasizing the importance of IC in FNAC. The authors concluded that FNAC IC benefits patient care. Cancer (Cancer Cytopathol) 2009. © 2009 American Cancer Society.

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