Excluding the laparoscopic omental biopsy of an undifferentiated tumor expressing Melan A, S100, chromogranin A, and synaptophysin, which led to the endoscopic identification of an intestinal melanoma with aberrant neuroendocrine differentiation, the other cases lacked any tissue-specific marker and were confirmed as CUPs (Fig. 4A). This evidence concerns the gene CHGA and neoplasm.