Impact of chronic lymphocytic thyroiditis on the diagnostic and intraoperative management of papillary thyroid cancer.

[BACKGROUND] Chronic lymphocytic thyroiditis is an autoimmune thyroid disorder and the most common cause of hypothyroidism in women. Many studies suggest that chronic lymphocytic thyroiditis contributes to a diagnostic challenge in thyroid nodules and may increase the risk of developing papillary thyroid cancer. This study examines preoperative clinical factors and tumor characteristics associated with papillary thyroid cancer among patients with chronic lymphocytic thyroiditis.

[METHODS] A retrospective review of prospectively collected data of patients who underwent total thyroidectomy between 2009 and 2020 at a tertiary institution was performed. Sociodemographic factors, comorbidities, surgeon-performed ultrasound, fine needle aspiration, tumor characteristics, and final histopathology were studied. Patients were subdivided into 2 groups based on final histopathology: chronic lymphocytic thyroiditis alone and chronic lymphocytic thyroiditis with papillary thyroid cancer. χ tests were used for independence among categorical variables, and comparisons were based on t tests.

[RESULTS] Of 2,200 total thyroidectomy patients, the majority of 250 patients with chronic lymphocytic thyroiditis were women (90.4%) and had a mean age of 50 (±13) years. All patients with chronic lymphocytic thyroiditis underwent preoperative ultrasound, 89.2% (n = 223) underwent fine needle aspiration preoperatively, and 25.2% (n = 63) presented with obstructive symptoms, whereas 53.6% (n = 134) had papillary thyroid cancer on final histopathology and 74.8% (n = 187) underwent central neck lymph node removal. When comparing patients with chronic lymphocytic thyroiditis alone with those with chronic lymphocytic thyroiditis and papillary thyroid cancer, no differences for sex, race, nodule density, nodule size, echogenicity, irregular borders, and number of nodules were identified, but there was a statistically significant difference for obstructive symptoms (37.1% vs 14.9%), multinodular goiter (55.8% vs 32.3%), microcalcifications (18.4% vs 36.6%), Bethesda III fine needle aspiration results (41.4% vs 27.4%), and central neck lymph node removal (58.6% vs 88.8%), respectively (P < .05). Preoperative fine needle aspiration in patients with chronic lymphocytic thyroiditis for papillary thyroid cancer had a positive predictive value of 92.9%, negative predictive value of 83.3%, false positive rate of 13.8%, and false negative rate of 8.8%.

[CONCLUSION] Although thyroid ultrasound features may have limited utility for malignancy, fine needle aspiration of index thyroid nodules still demonstrates a high positive predictive value in stratifying patients with chronic lymphocytic thyroiditis with papillary thyroid cancer. A higher level of suspicion preoperatively may be needed to avoid unnecessary lymph node removal for patients with chronic lymphocytic thyroiditis.