In case 66, a strongly cytokeratin-positive tumour with widespread visceral and bony metastases was diagnosed as a carcinoma of unknown primary, but following a poor response to treatment WGS was offered and showed a profile in keeping with osteosarcoma, including a TP53 intron 1 variant particularly characteristic of osteosarcoma [13]. The gene discussed is TP53; the disease is neoplasm.