[Preliminary study of patterns of level IIb lymph node metastasis in papillary thyroid carcinoma]

To evaluate the factors related to level IIb lymph node(LN) metastasis in papillary thyroid carcinoma (PTC). Method The medical records of 63 PTC patients were reviewed. The patients underwent neck dissection (ND) between January 2011 and December 2012, who were determined with pathologically lateral cervical LN metastasis. A total of 67 ND specimens were obtained and analyzed for LN involvement with respect to neck levels. The relation of level IIb LN metastasis with clinical factors, including age and sex of patients, tumor size, location, multifocality, extracapsular spread (ECS) and stage of primary PTC, coexistence of lymphocytic thyroiditis, distribution of metastasis LN in different levels, fusion and extracapsular invasion of LN were analyzed with univariate analysis and χ(2) test. SPSS 14.0 software was used to analyze the data.

Of 63 patients, 41 patients revealed thyroid tumor maximum diameter more than 1 centimeter, 26 patients with tumor located in the upper 1/3 thyroid lobe, 39 patients with multiplicity of thyroid tumor and 54 patients with ECS, 54 patients with pathological T3/T4a stage, 15 patients with coexisting lymphocytic thyroiditis. Among the 67 ND specimens, 12 specimens (17.9%) showed level IIb LN metastasis and the incidences of LN metastasis at level IIa, III, IV, V, VI, IIa+III, III+IV, and IIa+III+IV were 56.7%, 86.6%, 68.7%, 22.4%, 86.6%, 52.2%, 55.2%, 37.3%, respectively. Of the 38 ND specimens with level IIa LN metastases, 10 were positive in level IIb(26.3%). But of 29 ND specimens without level IIa LN metastases, only 2 were positive in level IIb. A univariate analysis revealed that level IIa LN metastasis was a significant predictive factor for level IIb LN metastasis (χ(2) = 4.219, P = 0.040).

The incidence of LN metastasis to level IIb is low in PTC, which is less when level IIa is not involved.