Criteria for diagnosing lymph node metastasis from squamous cell carcinoma of the oral cavity: a study of the relationship between computed tomographic and histologic findings and outcome.

Purpose: This retrospective study was conducted to determine the relationship between the computed tomographic findings for cervical lymph nodes (LN), histologic findings, and outcome in patients with squamous cell carcinoma of the oral cavity who underwent radical neck dissection.
Patients and Materials: Sixty-six patients were analyzed. Of these 66 operations, 43 were immediate therapeutic dissections in clinically N+ necks, and 23 were subsequent therapeutic dissections in patients whose necks were initially node free but progressed to positive nodes during observation.
Results: When the size criterion (area of the axial section) of nodal metastasis depicted on the scan of 45 mm2 was selected, almost 78% of LN were diagnosed consistent with the histologic diagnosis. As the size of the LN increased, the frequency of extranodal invasion also became higher, whereas patients with the higher histologic grades of malignancy often showed neck metastases with extranodal invasion in the early stage. Patients having LN smaller than 100 mm2, or without extranodal invasion, showed good outcome, whereas those having LN 100 mm2 or larger, with extranodal invasion, showed extremely poor outcome.
Conclusions: These findings indicate that it is possible to delay neck dissection in node-free patients until neck disease is diagnosed with timely CT examination, although great caution is necessary, especially in those with a high histologic grade of malignancy.