THYROID INCIDENTALOMAS - MANAGEMENT APPROACHES TO NONPALPABLE NODULESDISCOVERED INCIDENTALLY ON THYROID IMAGING

Background: The introduction of highly sensitive imaging techniques ha s made it possible to detect many nonpalpable nodules, or ''incidental omas,'' in the thyroid. Discovery of these lesions raises concerns abo ut their malignancy, but the optimal strategy for managing these lesio ns has not been clearly established. Purpose: To review evidence about incidentalomas, including prevalence and risk for malignancy, and to provide recommendations for their evaluation and treatment. Data Sourc es: Literature searches for relevant articles published in the past 15 years in major English-language medical journals, review of selected articles published before this period, and reviews of bibliographies i n textbooks. Study Selection: Three studies on autopsy findings, 11 st udies on ultrasonographic findings, and other reports on nonpalpable t hyroid nodules were included.Data Extraction: Data on the prevalence o f nodules on autopsy and in ultrasonographic series, palpation compare d with ultrasonography, the risk for malignancy in nodules found in ir radiated glands, the natural history of thyroid nodules, and the preva lence of occult cancer were collated and reviewed. Data Synthesis: Pre valence of thyroid incidentalomas estimated from autopsy studies range s from 30% to 60%. Studies comparing clinical palpation with thyroid i maging show a prevalence of 13% to 50%. Prospective studies of randoml y selected patients have reported a prevalence of 19% to 67%. The risk for malignancy in asymptomatic nodules found in nonirradiated glands is 0.45% to 13% (mean +/- SD, 3.9% +/- 4.1%). Conclusions: High-resolu tion ultrasonography is sensitive and capable of detecting many small, nonpalpable thyroid nodules. Most of these lesions are benign. For mo st patients with nonpalpable nodules that are incidentally detected by thyroid imaging, simple follow-up neck palpation is sufficient.