PMEL and melanoma: Thus, a broader panel of immuno-markers may be useful in distinguishing between metastases of malignant melanoma and other metastatic malignancies when the lesion is morphologically undifferentiated; Gupta et al. [15], in fact, reported four cases of morphologically undifferentiated melanoma that showed a positivity for HMB45 (two cases), S100 (one case), vimentin (three cases), NKI/C3 (two cases), NKI/Bteb (one case) and CK (three cases).