Papillary Thyroid Carcinomas in Patients under 21 Years of Age: Clinical and Histologic Characteristics of Tumors ≤10 mm

ObjectiveTo compare clinical and histologic characteristics of papillary thyroid carcinomas (PTCs) ≤10 mm in patients ≤21 years old with larger ones and with microcarcinomas in adults.Study designRetrospective study of patients with PTC diagnosed between 1983 and 2012. Medical records were reviewed and information about age, sex, tumor size, intra/extrathyroid extension, lymph node, and distant metastases were collected.ResultsPatients ≤21 years old (n = 93) and adults (n = 1235) with PTC were identified. Among the former, 34 had PTC ≤10 mm (37.4%) and among the latter, 584 had papillary thyroid microcarcinoma (PTM) (47.3%), P = .082. Patients with tumors ≤10 mm less frequently had extrathyroidal extension and lymph node metastases compared with larger tumors (8.8% vs 33.3%, P = .017, and 60.0% vs 95.2%, P = .001, respectively). The percentage of PTC ≤10 mm increased with age (7.1%, 32.0%, and 48.1% in age groups ≤15, 15-18, and >18 to ≤21 years old, respectively; P = .016). Mean tumor size was larger (6.8 ± 2.7 vs 5.8 ± 2.8 mm, P = .030), and lymph nodes metastases were more frequent (41.2% vs 18.6%, P = .003) in patients ≤21 years of age compared with adults with PTM. The frequency of multifocal cancers decreased between 1983-1992, 1993-2002, and 2003-2012 (66.7%, 53.6%, and 27.1%, respectively, P = .019).ConclusionsThe frequency of PTC ≤10 mm is low in children, increases in adolescents, and reaches that of adults at 18-21 years of age. Mean tumor size is larger and metastases to regional lymph nodes more frequent in comparison with PTM in adults. Whether their treatment and follow-up could be based on guidelines used for PTM in adults is questionable.