S100B and melanoma: In cases of cutaneous melanoma, S‐100B serum concentrations are a prognostic marker of metastatic disease.5, 7 Serum concentrations of S‐100B correlate with disease stage, although large variation is observed with or without S‐100B elevation.6 Previous findings suggest that S‐100B levels may be influenced by the melanoma metastasis location and by variations in the ability of melanoma cells to produce S‐100B.14, 15, 16 Together with the limited S‐100B elevation in patients with low tumor load, it is difficult to designate S‐100B as a solid indicator of recurrence.17