The levels of plasma exosome-derived Cx43 were considerably elevated in patients with melanoma whose tumor was situated in the skin, tumor size < 10 cm, with Clark level I–III, TNM stages IIb–IV, and had no lymph node metastasis as opposed to patients whose tumor was situated in the viscera or mucosa, tumor size ≥ 10 cm, Clark level IV–V, TNM stages IIb–IV and had lymph node metastasis (all P < 0.05). The gene discussed is GJA1; the disease is metastatic malignant neoplasm in the lymph nodes.