Cardiac tumour. Light micrograph of a section of an affected heart. Metastatic cardiac tumours (MCTs) involving the myocardium and pericardium are rare, with reported incidence of 1.5??0% of autopsies of cancer patients. Though these metastases may originate from any malignant tumour, they most commonly are caused by melanoma, lymphoma, leukaemia and carcinoma of the lung, breast and oesophagus. Most cardiac secondary tumours remain clinically silent (over 90%) and are often diagnosed post-mortem. Magnification: x250 when printed at 10 centimetres wide.