Tissue that gets cut out of people gets put in formalin to fix it. It then gets put into paraffin wax like we see here. They then get cut thinly and stained to look at a piece under a microscope. My guess is that the kidneys have failed in this patient, and that there's calciphylaxis (calcium, not being excreted in pee , binds with phosphate, also not being peed out, and deposits in tissues)