Background: In an attempt to determine the mechanism of cervical lymph node metastases, the authors studied the relation between lymphatic vessels in or around tumor tissue and lymph node metastases in patients with primary squamous cell carcinoma (SCC) of the oral region by enzyme histochemistry using 5'nucleotidase-alkaline phosphatase.
Methods: The subjects were 23 patients who had biopsy proven oral SCC. After enzyme histochemical staining, the cross-sectional dimension (referred to as diameter) of the lymphatic vessels were measured and analyzed in relation to the T classification of the tumor, degree of tumor differentiation, and mode of invasion.
Results: The average diameter of the lymphatic vessels in or around tumor tissue was significantly greater than that in tumor free tissue (P < 0.01). The mode of invasion correlated significantly with the lymphatic vessel diameter (P < 0.01). The diameter did not correlate significantly with the T classification (P range, 0.135-0.254) or tumor differentiation (P = 0.274). The following relation was found between the incidence of cervical lymph node metastases and the mode of invasion: 40.0% of Grade 2 tumors were positive for metastases, 71.4% of Grade 3 tumors were positive, and 75.0% of Grade 4 tumors were positive (grading was according to Jakobsson's classification).
Conclusions: Of the factors evaluated in this study, only the mode of invasion correlated significantly with the diameter of the lymphatic vessels. Although other studies have shown that tumor thickness and perhaps even perineural and blood vessel invasion may be equally important, the findings of the current study suggest that both lymphatic vessel diameter and the mode of invasion may be important factors in the prediction of cervical lymph node metastases.