Infarction of papillary thyroid carcinoma after fine-needle aspiration: case series and review of literature.

Importance Although infarction after fine-needle aspiration (FNA) is a rare occurrence, it is a known phenomenon that may lead to difficulties in interpretation for pathologists and in decision-making for head and neck surgeons. Objective To characterize our experience with infarction in papillary thyroid carcinomas (PTCs) after FNA and review existing cases of infarcted PTCs in the literature to better understand this phenomenon. Design, Setting, and Participants This was a retrospective case series and review of literature at a tertiary medical center (University of California, Los Angeles [UCLA], Medical Center). All patients who had a surgical pathologic diagnosis of infarcted PTC and who underwent FNA prior to surgery at UCLA from June 2006 to June 2012 were identified. There were 620 cases of PTC and 12 cases of infarcted PTC. Main Outcomes and Measure Demographic data, FNA cytologic findings, and surgical pathologic data were gathered for each patient. A comprehensive literature search for infarcted PTC was performed. Results Twelve cases of infarcted PTC were found in a total of 620 cases of PTC (1.9%). The mean (SD) time interval between the last FNA and surgery was 52 (35) days (range, 13-133 days). All patients received a diagnosis of infarcted PTC after thyroidectomy was performed. Focal infarction was found in 4 patients (33%), and near-total infarction was found in 8 patients (67%). Five patients (47%) had the follicular variant of PTC, making it the most common subtype in our series. A thorough literature search yielded 11 articles reporting a total of 26 cases of infarcted PTC after FNA. To our knowledge, our case series on infarcted PTC is the largest reported series in the literature. Conclusions and Relevance Although infarction of PTC after FNA occurs infrequently, it may lead to difficulties in histologic diagnosis. Awareness of this phenomenon and its histologic associations, along with careful reevaluation of the FNA and surgical specimens, is important for appropriate diagnosis and subsequent treatment. At this point, infarction in PTC should not alarm a head and neck surgeon to change management, but future prospective studies with a large population of patients with infarcted PTCs are needed to establish the impact of infarction on differences in treatment outcomes for therapies that may be used in PTCs.