The diagnosis of “Lambda light chain Multiple Myeloma stage III B; T10 vertebral plasmacytoma; JAK2 positive Primary Myelofibrosis” was done and it was decided to urgently start the treatment of multiple myeloma due to the advanced stage of the disease (anemia and significant bone mass loss), opting for the monitoring of PMF, as, at that time, the patient did not present any notable cytopenia/ pancytosis. The gene discussed is JAK2; the disease is plasma cell myeloma.