Isolated central nervous system relapse of multiple myeloma post autologous stem cell transplant- A rare presentation

•CNS relapse in multiple myeloma after ASCT without medullary relapse is uncommon.•Isolated CNS relapse is extremely rare with only 7 cases reported in literature.•Prognosis is poor with very short median survival after detection of CNS relapse.•Management is based on IMiD's and intrathecal therapy with radiation.