Serum MMP-13 levels show high sensitivity and specificity for the differentiation of invasive cSCC and cSCC in situ, and the prediction of lymph node metastasis, suggesting serum MMP-13 might serve as a valuable biomarker for early detection of cSCC invasiveness and monitoring of cSCC progression. Here, MMP13 is linked to metastatic malignant neoplasm in the lymph nodes.