Genomic exploration of the previous breast cancer lesion (with 90% of tumor cells) showed a different molecular profile thus precluding a potential common tumor origin with the skin tumor: absence of the PRKD fusion, high tumor mutational burden (21 mut/Mb), truncating variation of BCOR (VAF 3%), amplifications of ERBB2 (6 copies) and CCND1 (4 copies), complete loss of RB1 and several VUS. The gene discussed is RB1; the disease is neoplasm.