Skip metastases in thyroid cancer leaping the central lymph node compartment.

HYPOTHESIS

Discontinuous nodal metastasis, or skip metastasis, in thyroid cancer may display clinicopathologic features different from those seen in continuous nodal metastasis and thus may have a different prognosis.

DESIGN

Retrospective analysis.

SETTING

Tertiary referral center at a university hospital.

PATIENTS

Two hundred fifteen consecutive patients who underwent systematic central lymph node dissection for papillary, follicular, or medullary thyroid cancer and who on histopathologic analysis exhibited nodal metastases in at least 1 lateral or mediastinal lymph node compartment.

MAIN OUTCOME MEASURES

Various clinicopathologic variables that were stratified for tumor entity and type of nodal metastasis (discontinuous vs continuous).

RESULTS

Skip metastases (negative central and positive lateral or mediastinal compartments) were found in 13 (19.7%) of 66 papillary, 0 of 8 follicular, and 30 (21.3%) of 141 medullary thyroid cancers. After adjustment for multiple testing, skip metastasis was only associated with significantly fewer positive lymph nodes: 3.7 vs 12.9 nodes (r = -0.43, P<.001) in papillary thyroid cancer and 6.0 vs 17.1 nodes (r = -0.40, P<.001) in medullary thyroid cancer. No other significant correlation was identified with any other clinicopathologic variable.

CONCLUSIONS

Skip metastasis is an epiphenomenon of low-intensity nodal metastasis in thyroid cancer and entails a moderate risk of local recurrence. Consequently, clearing the central lymph node compartment should be considered when lateral or mediastinal lymph node compartments are involved.